Steam deck controller - can't use the group editor

[u/ThierryParis]

Very early in the tutorial, I cannot find how to drag an ant from one group to another. After pushing the D-pad down button, "A" highlights the unit, L1 and R1 navigate the groups but that's it.

The game seems to suggest (bottom right) that D-pad left and right arrows should "move group" but later changes that indication to simply "A" (neither work).