So the issue here seems to be that when adding multiple permissions at a time, the editor will trigger this failure. The log snippet shows a successful use of the editor, when addding a test permission, but then a failed use when editing a group.

LP Info
Java: OpenJDK 11.0.1

Running LuckPerms v4.3.94 by Luck.
 Platform: Bukkit
 Server Brand: Paper
 Server Version: git-Paper-524 (MC: 1.13.2) - 1.13.2-R0.1-SNAPSHOT
 Storage:
    Type: MariaDB
    Ping: 0ms
    Connected: true
 Messaging: Sql
 Instance:
    Static contexts: None
    Online Players: 1 (1 unique)
    Uptime: 1h 24m 21s
    Local Data: 1 users, 19 groups, 2 tracks

Console Log
https://gist.github.com/TheFlagCourier/cd38fbf3a74ceab5bb2dc89152bef1a9

Before Adding Perms

After Adding Perms

Appologies, I should really use the search function more often when filing a report. Duplicate / Not-A-Bug.

Conversely, not sure why the test permission worked, but the rest didn't.

Yup - basically your server can't connect to the network/internet and access bytebin.

Caused by: java.net.ConnectException: Network is unreachable (connect failed)