ASR Replication Issue - Error ID 70171

Hi. I'm new to using this forum so hopefully someone can help me

I have 2 x on-premise Hyper-V Windows 2012 R2 which replicate 10 servers into an Azure Recovery Vault which is used for ASR. I have a configured ASR policy which has been working for most of the year with no issues.

On Thursday last week I received notification to upgrade my Hyper-V Hosts from Azure ACS to AAD for ASR. I did this and it all went well and they're on Agent Ver 5.1.2700.0 (latest) and I updated the MARS Agents to the latest too as I had a notice about these needing updating to the latest version.

When I now list my 10 servers in Azure they are all RED and Replication Health is Critical and RPO column is blank. If I open ALL the servers they correctly state the App-and Crash resistance times : so why are they RED and stated as Replication Health Critical ??

The on-premise hyper-v replications says all is working and I used this article to check the finer points that replication is indeed being sent: https://docs.microsoft.com/en-us/azure/site-recovery/site-recovery-azure-to-azure-troubleshoot-errors#outbound-connectivity-for-site-recovery-urls-or-ip-ranges-error-code-151037-or-151072).

Any ideas ?