Could you please confirm the below scenarios,
- The connected VC have Powered on VMs with activate state?
- In UM appliance, which license category is used by vCenter Server - demo/Perpetual or VCPP ?
If assigned the license category is Demo/Perpetual then Reports will not have vRAM entries.
For reporting: check with your aggregator on what's acceptable to submit. If you open a support request the GSS team can reach out to the Remediation team to create a report, but keep in mind they will be reviewing all of the past data for accuracy also.
Usage Meter can't retro-actively retrieve usage by design. It would probably have to be re-architected to retrieve past usage. Chargeback Manager for Service Providers can do it (retrieve past usage by up to 6 months) because, by design, it's querying the vCenter database directly for consumption data. Usage Meter in the meantime is making hourly queries for state changes along with keeping a view session open (EventsMonitor in the logs of Usage Meter). If it misses a collection, or if the view session is interrupted, we're then missing the data.
The information is in vCenter still through a virtual machine inventory list; Usage Meter's method is a bit more accurate than only exporting that list though.