Ever since Sourcemod 1.7, Gamerules signature and offset has been removed from stock sdktools gamedata. You can check that for yourself, which made every function not work that came after it. Moving GameRules to Downtown gamedata solves this problem.
The other change was switching the debug to error for gamedata in vglobals.cpp and no longer block all functions if a single signature breaks. Makes sense to throw error for missing signature as opposed to only show it under debug version.