/teams commands keeps resetting after an indeterminate amount of time

On our realms survival server, each player has a team of their own for which only they are a part of. We use teams to disable floating name tags above our avatars, and to assign mobs to our teams. The problem is that for apparently no reason at all, our teams keep getting removed, or we keep getting kicked from them after some time.

The commands used by the owner of the realms are:

/team add (playername)

/team join (playername) (playername)

/team modify (playername) nametagVisibility hideForOtherTeams