I've a multi master & multi source replication setup working perfectly fine.
M1 -> M2 || M1 -> M3
M2 -> M1 || M2 -> M3
M3 -> M1 || M3 -> M2
As soon as I restart mysqld on M2 I'm missing a channel. And therfor the setup is broken. This is really weird. master_info_repository is set to table and SHOW SLAVE STATUS shows 2 lines & 2 channels BEFORE I do restart mysqld. After restart there's only 1 channel left.
There are no log entries in the error log that may hint to something weird at all.
MySQL Version 5.7.11