Ok.
Made a new local git branch
added level, added few walls, doors and signs
committed
added sign messages
committed
restarted game, sign messages were fine
removed all obstacles (but the signs) from the map, save, commit, sign messages
were fine
quit the game, started game, loaded map, sign messages were fine now

(did I do everything as you wanted now?)

Added new level, added some walls, doors and signs, added sign messages.