After following the install instructions everything seems to work just fine. When I use the /lp user info command, it shows assignment into the correct group. When I check the permission info, it shows the correct luckperms.* (wildcarded) permission.

Now when I launch the web editor, the same user is listed twice with double the permissions. So it looks like everything is configured correctly but the web interface is querying and outputting a duplicate row.

Try updating to the latest from https://luckperms.net this issue was fixed (or should've been)

Doh! I just installed the plugin from a hosting repository - didn't see the code was just updated last week. Thanks!