Wow classic in-game language change issues

When I try to change the language in the game, my chat in wow classic breaks. Basically, after changing my language (eng->russian and the other way) characters are getting randomly deleted and it becomes impossible to write anything longer than few chars. The way to fix it - write something in chat and cntrl+c/cntrl+x it, then it’s fixed until the next language change. Any idea why this happens and how to solve it?