I haven't used FPS unlocke,r but I've gotten this issue with vanilla SPT, and with similar mods. I think its a 3.11.3 issue... I don't know what causes the crashes though
I also think that there are breaking bugs in 3.11.3. For me there is a game breaking bug that occurs when I change the AI Ammount when starting the map to increase bots, and they die standing and unlootable, with guns floating just outside of their hands and bots torso shaking with firing sounds going on constantly, and the only way to fix this is to start a new account and never touch that setting! In previous versions of SPT, I never had these issues!