GMS1 IDE was never particularly stable when working with large extensions like GMLive (try right-clicking the GMLive extension, picking “Properties”, and seeing how long it takes for the window just to show up), but at some point something happened and now the IDE hangs when trying to open the project, or, if I manually remove the extension file and re-add it every time I open the project, hangs on game start while not responding to the debugger.
It is unclear whether this can be debugged in any way.