I guess, if the support is already working on this case, they will do their best to resolve this issue. As you said, failover works but it's during the reverse-resync process that this error is posted. I will be curious to know if there are/were any *cpeer* /etc/log/ems messages which might give some indication of any sort of warning or errors.
::> event log show -messagename *cpeer*
Also, does ::> cluster peer show -instance on both source & destination, shows Availability/Authentication as Available/ok? and run this cmd as well ::> cluster peer health show (Share the output if you could)
In the worst case, it may require support to run diagnostic commands to fix/edit some entry in internaldb (I am guessing). Hence, please do let us know once you have this issue sorted and you would like to share the same.