I've not activated the DEF Skies mod. But I was wondering if perhaps I'd made a change to the map load.ini files when I discovered the issue in my own installation and wanted to make sure the vanilla 4.3.0 refers to SrbijaDrvoTL.tga (instead of SrbijaDrvo.tga) that genXgamer found in his dump folder. I've been playing around so much lately with these files I don't trust my archived extracts anymore.
I had a similar loading issue with the Kemijarvi-Alakurtti (Winter 1940) - Mixx map and found a forum thread that suggested a change from Tree0 = land / POLAR_CIRKLE / AlteredBush6aw.tga to Tree0 = Trees \ AlteredBush8aw.tga which worked for me.
https://www.sas1946.com/main/index.php/topic,65738.msg721210.html#msg721210I'm going to try loading every map in FMB over the next few days (weeks?) to ensure I haven't screwed anything else up somewhere along the line. I know that has surely already been done by Vampire Pilot in his extensive testing before the newest release and I don't doubt anyone here but myself. I'm convinced it has something to do with my hex files, because when I removed all of them the game still loaded just fine but I received errors when trying to fly missions due to map loading issues so somehow there's a connection between the class files and the map loading sequence even though they're not included/referenced in the load.ini files as far as I can tell.
When I extracted the SFS archives it really gave me a chance to appreciate just how fabulous this latest update is compared with the last. For example, in total I now have around 66,000 hex files, whereas in my BAT 4.2.3 installation I'd found around 280,000 (some of these due to added mods)! That's an awful lot of trimming! Amazing stuff! Simply beautiful!