Remove all Export.lua entries, either comment out like -- dofile, or rename the file for testing so it is not loading the export lua functions.
Load into a standard instant action mission
Already tried that. It only crashes if I have the SimAppPro entries in the export.lua file, even when on their own. I normally have other entries in export.lua and they have always worked fine. I also did a DCS update cleanup and that made no difference either. What I haven't done yet trying it with a clean Saved Games\DCS.openbeta directory, i.e. no mods etc at all. WinWing haven't found an answer yet either but they are gibing me some remote assistance tomorrow to try to get to the bottom of it.
In the mean time here is an error log:-
dcs.log-20230919-134752.zip