Just to confirm: No solution up until today. I am not able to load any plane with ISG gauges included. Any idea, what might be the reason?
I still think its memory related. It would explain why it works sometimes, and not other times.
It is a large gauge, and maybe there are times you don't have the resources to load it, depending on what else you may ahve loaded in FS.
Try going to an area that has almost no scenery (desert, outback etc). Then try and load a default plane with ISG gauges there.
If it loads consistently, then it could be a memory issue.