How, with Gremlin, to return properties from in-vertices the same as I do from out-vertices? (Not as

I'm trying to start traversing from one set of labelled vertices, then get all their in-vertices connected by a particular kind of edge, then from there, return a property of those in-vertices as objects. I can do this same thing with some out-vertices starting from the same set of labelled vertices with no problem, but get a "The provided traverser does not map to a value:" error when I attempt it with some in-vertices.

I have found a workaround, but it is not ideal, as it returns the desired property values as arrays of length one.

Here is how I do the very similar task successfully with out-vertices: g.V().hasLabel('TestCenter').project('address').by(out('physical').project('street').by(values('street1')))

This returns things like

==>{address={street=561 PLACE DE CEDARE}}
==>{address={street=370 N BLACK STATION AVE}}

This is great!

Then I try the same sort of query with some in-vertices, like this: g.V().hasLabel('TestCenter').project('host').by(__.in('hosts').project('aCode').by(values('code'))) and get the above mentioned error.

The workaround I've been able to find is to add a .fold() to the final "by" like this: g.V().hasLabel('TestCenter').project('host').by(__.in('hosts').project('aCode').by(values('code')).fold()) but then my responses are like this

==>{host=[{aCode=7387}]}
==>{host=[{aCode=9160}]}

What I would like is a response looking like this:

==>{host={aCode=4325}}
==>{host={aCode=1234}}

(Note: I am not sure if this is relevant, but I am connecting Gremlin to a Neptune DB Instance)