This was a bug brought to my attention by Boom5 and Baraka.
When the "Set current and max hit points of player 'A' to value 'B' " action is used in a trigger, it will prevent all the following actions from being executed. This seems to be a new bug and is breaking older maps.
Trigger action in question:
I couldn't recreate the bug, and Baraka has a theory that it only occurs in existing maps.
Anecdotal account: I was able to copy the bug over to a new map from Boom5 a while back. Unfortunately I don't have the map saved.