Player Tab is not Refreshing (modded server)

First, let's check if the client has mods installed. If so, follow these steps:

1. Close the server.

2. Rename the "mods" folder to "mods-temp".

3. Start the server.

4. See if that cleared the issue. If it did, then the issue comes from one of the mods. To know which mod is causing it, start uploading the mods one-by-one (starting with the most suspicious ones that are network/tab/chat related).