I'm having the same problem, trying to have an unpacked room load custom variables. I'd appreciate help sorting this out.
I tried setting up gmlLive and putting
room_pack_eval_script = live_execute_string;
into the create event for the object but I get the following error-
"Can't execute code for inst_70184F7E:Properties - please assign an evaluator script to room_pack_eval_script (see doc)"
I'm using 2.3 Latest Stable Version.
Also probably unrelated but GMLive.gml floods the Syntax Error checker of GML to the point it gives up and stops checking other scripts.
most of them say- variable this referenced only once