I have a Canvas App form that references a Dataverse table.
One of those fields is "Project Manager" -- which is defined as a lookup to AADUsers.
It all works fine EXCEPT when I turn on "Is Searchable" to TRUE
When I set "Is Searchable" to TRUE,
I get a red X and the error it returns is

I've tried different values in the field SearchFields property, even clearing it completely.
This dropdown for an AADUser lookup field just doesn't seem to like having Search turned on.
Has anyone else encountered this?
Has anyone else successfully placed a Canvas App Dropdown for an AADUser lookup that supports Search?