Titan needs HRV readings from Apple Health to show HRV, score Recovery and track Stress. When HRV is blank, work through the checks below in order.
01Wear your watch to bed
Apple Watch records HRV in the background a few times a day, at times you do not pick. A night of sleep gives it hours of stillness and the best odds of a reading. Recovery uses every HRV reading taken during your main sleep session. With no sleep session, it uses readings between 10 PM and 10 AM.
A night with no HRV reading leaves Overnight HRV blank on the Recovery screen, and Recovery shows an estimate marked "No HRV recorded overnight". The HRV tile on Today and the Vitals screen use all of the day's readings, so they can still show a value on that day. A day with no reading at all leaves them blank.
02Confirm Health permission
iOS never tells an app which read permissions you denied, so Titan cannot warn you. In the Health app, tap your profile picture, then Apps, then Titan. Turn on Heart Rate Variability, plus Heartbeat Series if you use RMSSD. The Health Permissions row at Settings > Health & Connected Apps opens iOS Settings for Titan. Open Settings from the avatar on Today, then the gear on You. See Health permissions.
03Check the RMSSD setting
Use RMSSD for HRV, at Settings > Recovery & Sleep, tells Titan to calculate RMSSD from beat-to-beat data instead of reading Apple's SDNN value. That data lives in the Heartbeat Series type in Apple Health, and Titan needs read access to it. Titan does not fall back to SDNN. If Heartbeat Series access is off, or your source writes HRV without beat-to-beat data, HRV stays blank.
Turn on the permission or turn off RMSSD. Titan rebuilds your Recovery history with the new method on its own.
04Check your source filters
Settings > Health & Connected Apps has a row for HRV. If that row shows a device name or a count instead of All Sources, Titan reads HRV only from the sources you allowed. A new watch is a new source and stays excluded until you allow it. Open the HRV row and tap Reset to All Sources. Data sources covers the other controls on that screen.
If HRV is still blank after all four checks, reach out through the contact page.
