we have very similar issue, SRM broken for entire organisation.  We downgraded SRM to our last version from a backup (8.5)  and got the same initiator errors.  

"Failed to promote replica devices. Failed to promote replica consistency group '*****'. Skipping failover operation for device group '******' as initiators were missing for one or more hosts."

Whats weird is initial failover worked fine, run a failback and thats when we got above error.   Thats how its been since.

Have a case running with vmware now who just seem to blame storage from SRM logs, but no changes have happened storage side to cause this.