Thanks for the reply. We implemented a couple changes that may have fixed this but in general here are some things we tried:
1. Remove and re-add the cluster into OCPM (warning, you will lose historical events)
2. Rediscover the cluster in OCUM
3. Upgrade to OCUM v7 (latest minor release)
4. Renew SSL certs for the cluster
And one other thing i stumbled on that may be an issue for you too if you use underscores in your DNS names for your hosts (cluster mgmt lif's)
5. https://community.netapp.com/t5/Data-ONTAP-Discussions/Problems-with-an-in-the-DNS-name-with-OnTap-9-3/td-p/138712
This became apparant when we upgraded to ONTAP 9.3P2 and i could no longer reach the system mgr interface via name but could reach it via IP. (This was because the DNS entry for the cluster mgmt lif included an underscore which is not permitted by 9.3 standards i guess)