EFM Exporter indicates "No New Data" in the TOP Server Event Log Despite Known New Data in the Meter

I'm using the TOP Server EFM Suite to collect EFM history from some flow meters and export that data. I have multiple poll groups and multiple EFM Exporters of different types. The EFM polls are completing successfully but the TOP Server Event Log posts the following event:

No new data for meter <Meter Name> exporter <Exporter Name>.

Resetting the cache (or rolling back the EFM pointer) results in a successful export and confirmed new data that should have resulted in a normal scheduled export but did not. I've confirmed that none of the proposed problems in the plug-in help file for this event apply to my configuration. What could be the problem?

So for the referenced event in the TOP Server event log, there is one other possible cause of the message aside from those documented in the plug-in help. This message literally means that the driver polled the device based on the current EFM pointer file for that specific meter and attempted to retrieve any new EFM history data that had occurred since the last poll. However, this message indicates that there wasn't any new data when comparing what data was available in the device compared to the last event polled according to the EFM pointer file created by the driver.

The EFM pointer file is updated after each EFM poll and EFM pointer files are specific to each EFM meter configured in your TOP Server project. It is important to understand this because the EFM Exporter plug-in can only export data when there is new data to be exported.

Since there is no restriction in the EFM Exporter plug-in configuration on having multiple poll groups with one or more of the same meters in your configuration added across EFM poll groups in the plug-in, it is technically possible to have overlapping poll groups with the same set or a subset of the same meters. As such, this overlap can result in a previous EFM poll for one of the poll groups updating that meter or meters' EFM pointer file already. As such, when the overlapping poll group triggers a scheduled EFM poll for that meter or meters, there technically isn't any new data available because it has already been polled and exported previously for the other poll group.

The solution to this issue is to either remove the affected meter or meters from one of the overlapping poll groups in the EFM Exporter plug-in or to disable the overlapping poll group.

Alternately, if you have a specific use case requiring more than one poll group for one or more meters, you will need to review the desired export behavior to find a timing for each poll group that allows the desired data to be exported at the desired time. It's important to understand that you can have more than one EFM exporter configured for the same poll group. So if your use case involves needing to export the same EFM history data for the same meters to two or more different export formats (i.e. FlowCal and PGas, FlowCal and CSV, etc), the best practice would be to simply configure all of those exporters under the same poll group, since it is the poll group that ultimately controls the EFM polling schedule.