Changes to Decks and At-Start stacks not visible to opponent

I’m trying to create my first module, which at the moment has a single board with a deck of cards and a at-start stack of pieces.

When I play the module online, any changes made to the at start pieces or the cards are not visible to the other players.

Pieces from the pieces palette work fine, it’s just the ones in decks or at-start stacks that have a problem.

What am I doing wrong?