This page describes some steps for trouble shooting per capability for example when data is missing.
In general you can check table RCA_INBOUND_LOG in FRUN via SE16, MESSAGE_TYPE="E" will filter on errors. Here you can see errors of data that are sent to FRUN. However there might be already problems in collecting data either in the agent application, in the managed system or on the way.
HANA Metrics are collected via an operation of the SAP Hostagent. Check in Agent Administration for the HANA system if the collectors are running:
ABAP work process samples (/SDF/SMON) are collected via a RFC from the SDA usually with user SDAGENT. Check in Agent Administration for the ABAP system if the collector is running:
The page ABAP Performance does not display any data which could have multiple reasons: