This may explain the situation: https://support.fatshark.se/hc/en-us/articles/360005177317--PC-Help-Why-have-my-items-disappeared-
This thread was added on April 06, 2020, with posts from FatsharkJulia, KaelusVonSestiaf.
If you lost your character levels too (not just items) then it’s a different issue, however.