I have come back with some more details, I've been playing since version .6 or so after seeing a video on reddit on your mod. I'd download the update, paste xcom assets, run X-Files mod, and copy over the saves and the options config from the last version-- keeping track of advanced options and opening at a certain aspect size and what all.
At version .7 the research to reveal all agents PSI strength before PSI Lab training had changed. Looking at the research tree I discovered Alpha Werecat and the Black Moon mission. Just changing a Monsters Hunt mission into Black Moon kept crashing as a Region variable was too large (even -1 or 1) and even Blood Moon edits; I then changed strategy and kept a save minutes before midnight of the next month. And then I manually copied missions such as Underwater City, Golden Diplomatic Envoy, and a few more terror and alien base missions into the main save to continue from.
Looking at the new AlienMissions in the save file I found that they displayed a uniqueID, and having copied from the "same month" several times the uniqueID duplicated among a few of them. So I manually edited them sequentially.
I thought it strange though that the Mission ID was so behind what the Diary was saying. i.e.
I don't how this affects behavior changing the alien race after reloading, but I figure since
doesn't record the alien race but issues ID about itself (and I have to stress I'm speculating and theorizing) mission that when reloading it looks for what it should be on what is available in the save and that a UFO thread may have issued the same ID. So when playing it correctly (detect, attack UFO, engage mission) registers which race was just crashed. (The glitch switching to Chtonite Base even on a Snakeman Terror UFO)
So for now I'll use the Save Scum option to keep single UFOs to quickly engage without worrying about too many Chtonites and then delete most of them before next month so the game will properly reset/spawn the UFO missions.
Manipulating the save file like that is the limits on my programming knowledge so I hope I have given enough information to replicate this unintended behavior. Thanks for crafting this excellent mod for a great game we all love.
