So I've been having this problem with UTeam on my Sandbox Server.
I decided to re-name a few groups with UTeam like making superadmin --> owner etc.
Nothing really went wrong, all UTeam does is re-name the group to make it look like a different group. But one tiny thing went wrong after I created the teams:
Nobody could speak.
And I know what the problem was: When I created the teams, only other players with the same rank could hear each other.
I tried multiple things: sv_alltalk 1, sv_voiceenable 1 etc. And nothing worked.
I really need to fix this problem as soon as possible. It is very bizarre.