Bug description
On paper server, I created group and invited someone. And when I click G, there was no group. Then I quit and rejoin the server, I can't even invite and there's no group.
(is it normal to kick a player if he quit the server?)

Steps to reproduce the issue

1. click G
2. Click Create Group button
3. set the name and click create button
4. Nothing changes. Screenshot below doesn't appear and just nothing.
5. But I can invite someone

Expected behavior
4. screenshot below appear

Versions

• Minecraft version 1.12.2
• Paper Version 1620
• both of them are 2.4.0 pre 3

Also, I did port forwarding on UDP 24454 and set firewall inbound rule

Please don't report bugs of pre release versions here. All feedback to that version should be in #beta-testing-feedback