Failed to resolve anonymous Party during integration test

I developed a simple state "item" that represents items a seller will sell to a group of anonymous buyers. I wrote flow tests and everything seems to be going OK. I wanted to also implement integration tests to confirm my logic is working properly. My flow failed due to the fact that the seller node started cannot resolve the buyer from its public key. I was able to reproduce the code without any of my own code. I feel like I missed a registration step or something but then again the seller node can resolve the buyer node using the X500 name. I'm a bit perplexed by why I'm having problems resolving the buyer node through its public key.

To replicate, clone cordapps-kotlin-template and replace the contents of DriverBasedTest.kt with the following code, run gradlew integrationTest.

import net.corda.core.identity.AbstractParty
import net.corda.core.identity.CordaX500Name
import net.corda.core.utilities.getOrThrow
import net.corda.testing.core.TestIdentity
import net.corda.testing.driver.DriverDSL
import net.corda.testing.driver.DriverParameters
import net.corda.testing.driver.NodeHandle
import net.corda.testing.driver.driver
import net.corda.testing.node.User
import org.junit.Test
import kotlin.test.assertEquals

class AnonymousTest {
    private val seller = TestIdentity(CordaX500Name("Seller", "", "GB"))
    private val buyer = TestIdentity(CordaX500Name("Buyer", "", "US"))

    @Test
    fun `anonymous resolution test`() = withDriver {
        val sellerUser = User("sellerUser", "testPassword1", permissions = setOf("ALL"))
        val buyerUser = User("buyerUser", "testPassword1", permissions = setOf("ALL"))

        val sellerHandle = startNode(providedName = seller.name, rpcUsers = listOf(sellerUser)).getOrThrow()
        startNode(providedName = buyer.name, rpcUsers = listOf(buyerUser)).getOrThrow()
        val resolvedNameBuyerA = sellerHandle.resolveName(buyer.name)
        assertEquals(buyer.name, resolvedNameBuyerA)
        val resolveFromAnonymous = sellerHandle.resolveFromAnonymous(buyer.party.anonymise())
        assertEquals(buyer.name, resolveFromAnonymous)
    }

    // Runs a test inside the Driver DSL, which provides useful functions for starting nodes, etc.
    private fun withDriver(test: DriverDSL.() -> Unit) = driver(
            DriverParameters(isDebug = true, startNodesInProcess = true)
    ) { test() }

    // Makes an RPC call to retrieve another node's name from the network map.
    private fun NodeHandle.resolveName(name: CordaX500Name) = rpc.wellKnownPartyFromX500Name(name)!!.name

    private fun NodeHandle.resolveFromAnonymous(name: AbstractParty) = rpc.wellKnownPartyFromAnonymous(name)!!.name
}

The test result is as follows:

kotlin.KotlinNullPointerException
    at com.template.AnonymousTest.resolveFromAnonymous(DriverBasedTest.kt:40)
    at com.template.AnonymousTest.access$resolveFromAnonymous(DriverBasedTest.kt:15)
    at com.template.AnonymousTest$anonymous resolution test$1.invoke(DriverBasedTest.kt:28)
    at com.template.AnonymousTest$anonymous resolution test$1.invoke(DriverBasedTest.kt:15)
    at com.template.AnonymousTest$withDriver$1.invoke(DriverBasedTest.kt:35)
    at com.template.AnonymousTest$withDriver$1.invoke(DriverBasedTest.kt:15)
    at net.corda.testing.node.internal.DriverDSLImplKt.genericDriver(DriverDSLImpl.kt:1289)
    at net.corda.testing.driver.Driver.driver(Driver.kt:197)
    at com.template.AnonymousTest.withDriver(DriverBasedTest.kt:33)
    at com.template.AnonymousTest.anonymous resolution test(DriverBasedTest.kt:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:110)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
    at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:38)
    at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:62)
    at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
    at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
    at com.sun.proxy.$Proxy2.processTestClass(Unknown Source)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
    at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
    at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:412)
    at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
    at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
    at java.lang.Thread.run(Thread.java:748)