A device that stopped reporting looks identical to a person who did no work. Always separate the two before drawing a conclusion.
Check first
- Device status for the affected users — is "last seen" recent?
- Data-quality indicators on the view — Optimetrix flags periods with missing or thin data.
- Whole-team drops on the same day → almost always an update, a network change or a certificate issue, not behaviour.
Backfill is not possible — data starts when the agent runs. Note the gap and move on.