Google is your friend here:
https://newworldinteractive.com/insurgency-sandstorm-patch-4/
From patch notes: Year 1, Year 2, DLC, and purchased cosmetics unlocking issues should be solved for SOME players.
Try a fresh install, maybe it will help. 🤷♂️
Well it’s neither mentioned as a “Known Issue” nor “Fixed” in the latest Patch Notes.
https://newworldinteractive.com/insurgency-sandstorm-patch-4/
Which is weired since it’s mentioned hundred times a day and happens really often across all platform.