If rides show up in LeCoach as 'Untitled Activity', or with no power, heart rate or other data, the cause is almost always the same: the activity reached Intervals.icu via Strava, and Strava's data policy strips the details.
LeCoach marks affected activities with a warning and offers a fix wizard that walks you through the solution.
The fix in short
On the Intervals.icu connections page, connect the platform you actually record with (Garmin, Wahoo, Zwift, MyWhoosh, ...) and enable 'Download activities'.
Press 'Download old data' there to backfill past activities with full data. Intervals.icu de-duplicates automatically.
Run a Full Intervals.icu Sync in LeCoach Settings - Integrations.
The full background and edge cases are in Activities (from Strava) are not showing up in LeCoach.