So it happened 2 more times to me. Last time was last night, I had the season roll over, then I did a trading with a caravan, got ambushed, fended it off, cleaned up after the battle, re-organized my military, saved and went to bed. Today I opened up my last save and it was all the way back at my seasons save. (I'm using LazyNewbPack[0.31.16][V5.2] with Stonesense_Slate_2.2, soundSense_20_98, and DwarfTherapist v0.6.4) Could any of these be messing up when I manually save because I do know these utilities access DF memory.
This kind of thing happened to me a couple of times too - I also use Lazy Newb pack. I'm not sure exactly what happened , but I was just saving using the game's interface, not messing about with the file system. After losing a total of about 20 hours of play time, I'm extremely careful now. Problem is I'm not sure what to be careful about. I've finally figured out that saving overwrites a savegame, and does not create folders like the seasonal save does.
I have tried looking at the modified date on the folders to make sure my game actually does save get saved (not sure what I would do if it didn't anyway, since the game boots you out on save... so if it's not saved, I'm SOL right?).. but anyway I've just double checked and for some inexplicable reason the folder's Date modified field DOES NOT CHANGE on save. My 'current' folder has the correct date modified, but none of the other folders match it. If my game was actually saved today, one of those folders should have today's date as Date Modified, should it not?? Yet I load my game, and all is fine, today's save worked.
Edit: I guess what probably happened is I opened one of the 'backup' saves instead of the 'RegionX' save; I was probably assuming that the correct load was the one matching the season and year of my last save (WRONG)... On my current fortress I've deleted the RegionX folder and after doing that I haven't lost any more saves... however I do NOT recommend deleting the regionX folder, since from reading the rest of this thread it seems that's the important one... bassically,, follow that other guy's advice I guess... NEVER load a backup save, only load RegionX.