Error message - Remove from Play

I noticed that my published module for Brief Border Wars, when played on a more current version of Vassal, has started to generate a bad data error message:

Bad Data in Module: Piece: White 7C3M Trait: Send To Location - Remove from Play - Remove from Play => Alt+E Source: Zone=Side 1 Dead Pool Error: Zone not found.

This is generated when I have dealt cards onto the table and right click a card with the intent of sending the card to the private hand of one of the players.

When I inspect its Prototype Definition (White Card or Gray Card), there is no trait that uses the Alt-E command.

The module seems to work fine otherwise.

Any ideas of how to resolve this problem? Also, I have been away from module development for at least two years and am a bit rusty.

If you aren’t sure what piece has the command on it, the Editor has a search facility that can scan everything searching for a given keystroke or snippet of text. So in this case, searching for "Remove from Play”, Alt+E, or "Side 1 Dead Pool” ought to bring up where those are getting invoked.

The error message is generated by various pieces with the White Card or Gray Card prototype. I didn’t see anything in the prototype that issues the Alt-E command when I examine the properties, as if there’s something hidden or it is looking elsewhere.

I see this usage of Alt+Ein the White Card prototype: