MySQL Forums :: Replication :: Replication began to work not always, not right away

The Host (in the PROCESSLIST) is NULL ??? Please describe the topology of your Master and Slave -- same or separate machines? TCP/IP connection? Other?
(I don't know what to make of that. I hope the Master and Slave are not on the same machine.)

SHOW MASTER STATUS; -- on Master
SHOW SLAVE STATUS \G -- on Slave
(I'm fishing for binlog/replicate-do/ignore and anything else out of the ordinary.)

Check the clocks on the two machines; the seem to be at least 8 seconds apart.
(I don't think this could cause the trouble, but you probably should fix it.)

> `ip` varchar(20) NOT NULL,
Overkill for IPv4; inadequate for IPv6.
(Unrelated issue.)

Please do these on both machines:
CHECK TABLE ibf__uag_banlist;
CHECK TABLE ibf__uag_gvars;
(Since you are using MyISAM, a REPAIR may be needed.)