When moving issues with bulk change, you are warned that versions are not retained from one project to the other:
"Issues not in the project Apogee Portal will not retain values for Affects Version/s";
"Issues not in the project Apogee Portal will not retain values for Fix Version/s".
(Besides, I think the Retain check box there is therefore obsolete).
But more importantly, you are not warned for custom fields which also use that version list (Version picker field). The retain check box is available, so you assume these values will be retained.
But since it uses the same values as Affected version and Fix version, of course it is not retained and written with the value you selected (default Unknown).
I would expect the same warning as for Affected/Fix version.
The same is valid for Assignee/Reporter that is not a member of the new project. This field is filled in as Anonymous. Understandable, but there was no similar warning as for Versions.

Consequence: after I did this Move, I had to correct all the Verified in Version values manually.