Check the registered instance by running:
asnp Citrix*
Get-ConfigRegisteredServiceInstance | measure *For 3 DDCs running on v1903 it should be 192*
If it doesn’t match then check instances of each DDC to see which one has missing instances.
Get-ConfigRegisteredServiceInstance -ServiceAccountSID “SID of DDC” | measure *Run get-brokercontroller to get SID of DDC*
Remove rogue DDC from site which has 0 service instances registered.