ABB 800xA Client Historian trend not working
If I were to guess, something is not alright with the 800xA History services.
I prefer using the less complex but for pure operator trending and reports perfect fitting Basic History service. What if you (for test purposes) create a Log Template solely based on the (I assume redundant pair of Basic History running in 8520SVR0001 and 8520SVR0002) and deploy a property log somewhere - does that Basic History log work across all your clients? If yes, your problem is likely within 800xA History.
If not, have a look at affinity and firewall. It is very simple to "lock out" a client from a service by making a mistake in Affinity. *Always* terminate each affinity declaration with the All Nodes node group object. Only service groups and providers created by the SCC > Configure System task are automatically exempted from firewall. A manually created service need a manually made firewall exclusion.