Actions Already Set Prevent Context Hiding
If a frame already has an action on it when the frame is merged/unmerged, the list of permissible actions does not update with the frame's merged status. For instance, merging a frame, giving it a random action, and unmerging it prevents you from setting a Game Over on that frame. Giving the frame a random action and then merging it allows it to pick from any action.
Implications of the invalid trial data are not known.