NametagEdit is a great plugin but I have encountered many problems with it, as well as some people on the Aternos discord, complaining that it's broken and doesn't work properly.
I believe you just need to update it again. Here's the most common issue I've encountered/seen.
When you create a group prefix/suffix and it's own permission (i.e nte.member), then add the permission to a rank. The players will receive the prefix/suffix, but once a player changes ranks, such as from Member to Helper, the prefix/suffix doesn't. You can't clear it of their name/uuid, the only way to get rid of the previous prefix/suffix is to change it's permission (from nte.member to nte.*anything*).
This is annoying because every time you promote/demote a player and just give them a different rank, you will need to go into the config file (or through commands) and change the permission to something new.
~Snoop
The Aternos forums are now deprecated
Learn more about this change here.
For help regarding Aternos, we recommend you to visit our support center.