When 1.63 came out, all of a sudden my Bandicam stopped working. At first I thought that it had something to do with the new streaming rendering engine,
so I went to their forum and sure enough, this problem was listed. Apparently Gaijin left out a command code that hooks to bandicam.

If you're having this issue, here is the fix.
Open the WT folder. C:Program filesX86/warthunder.
For Steam it's, C:Program filesX86/steam/steamapps/common/warthunder.

Open the config.blk with notepad and add the following command to the first paragraph. hooks:b=yes
save and preferably make it read only so that it doesn't change when you open the launcher. Ignore the warning msg and choose run game anyway.

GL