I was rank 24, got to 25, lost it, returning to 24.

Ranked all the way up to 26, lost it, returned to 25.

Ranked up to 27, lost it, returned to 26...

This is extremely annoying.

Also, i lost one weapon unclock.

Oh, now i have scarab but can not access it, since i went back to 26...

maybe you play at unranked server..try it to search ranked server

I believe that all the players have lost some amount of xp, I for one fell to lvl 32 from 33 yesterday, guess no choice but just to lvl up again. And they are probably working on fixing it.