No HRM Detected - Fitness App

Hi everyone, I have a problem with the fitness app on iPhone 14 Pro (iOS 26.1): my Apple Watch SE (WatchOS 10.6.1) is not detected as a heart rate monitor. iPhone and Apple Watch are paired; workouts started on the Apple Watch are correctly synced with the iPhone with all the complete data (including heart rate) but, despite this, the app does not detect it as a heart rate monitor.

I've already tried restarting both devices. Unpaired and re-paired both, first time by setting up Apple Watch from backup and second time by setting it up as new Apple Watch. None of this solved the problem

[Edited by Moderator]