SNAFU

Tropical/Swamp map tileset mod comes with its own integrated ambient sounds. Try renaming 'sounds_gc' file in 'Xenonauts\assets\mods\Tropical and Swamp Tileset' folder to something else, and see if that fixes the issue. Note that this will disable the ambient and map-specific sounds for the Tropical and Swamp maps, but should be a small price to pay compared to freezes and crashes!

I've been experiencing this issue consistently when either Ultimate Ambient Sounds is enabled or (most notably) on the Tropical/Swamp tileset, which has integrated ambient sounds. I've kept Ultimate Ambient Sounds turned off for my current campaign, but from my testing, save type does not seem to matter. Autosaves, quicksaves, and manual saves on a tropical/swamp map all manage to load the first time fairly consistently (sometimes it freezes on initial load, but this seems to thankfully be rare); It is when attempting to load *any* save while *on* the map, or when you would otherwise transfer to the Geoscape (mission success, mission abort, team wipe) that the game freezes for me. One minor workaround that's been mentioned is to load a save that is on the Geoscape, THEN load the GC mission on the tropical/swamp map, and then attempt to finish the mission without attempting to reload any saves. Also, the game appears to freeze under certain conditions that I think relate to suppression that I've been unable to fully discern while on tropical/swamp maps (and I presume, ALL maps when you have Ultimate Ambient Sounds enabled); it seems to happen most consistently if using a weapon with large bursts, like vehicle-mounted MG or an LMG, though I've also seen it happen with rockets or in circumstances where more than one unit (friendly and enemy, and including already suppressed units) *might* have become suppressed (impossible to be sure because... well, the game freezes!). Fortunately, I think I just now managed to discover a workaround for the Tropical/Swamp maps at least! I went ahead and renamed the 'sounds_gc.xml' file in Xenonauts\assets\mods\Tropical and Swamp Tileset to try to disable the ambient sounds and it appears to have made all of the above issues disappear. Saves now load from tropical/swamp maps, game correctly transfers to Geoscape and the suppression freezes I've described appear to have disappeared as well. I'm still doing some testing to see if this might introduce other issues on tropical and swamp maps, but so far I've not encountered any. Hope this helps anyone else experiencing this incredibly frustrating issue.