Can't pin any comments on TikTok? How to fix it?

Hey! I can't pin any comments on TikTok. I already tried to report the problem like 10 times, deleted and re-installed the newest version. Still nothing. I have this feature on two of my accounts(2-3 years old), but on other three accounts (about 3 month old) there is nothing. Any way to fix this issue? Thank you :)