I had the problem that I was unable to select any weapon in ttt.
After some research/testing I discovered the problem is on this mod. So after disabling it everything went back to normal.

In the local game console there is a message saying: wepswitch - unknown command (or very similar). Is this only applying to me, or do you have problems too?

There is at least one other discussion about this topic here:
https://steamhost.cn/steamcommunity_com/app/4000/discussions/1/1867245566135042367/