Apple Watch SE 2: Multiple features not working after overnight charge

Apple Watch SE 2 suddenly stopped working properly after being left on charge overnight

I have an Apple Watch SE (2nd generation, 44mm). Last night I left it on the charger as usual, and when I woke up and started using it, several functions had suddenly stopped working.

The unusual part is that the Watch itself is still functioning, and the sensors appear to be active, but several wrist-related features are no longer behaving correctly:

• Raise to Wake no longer works.
• Incoming notifications no longer wake the display. I have to touch the screen to see them.
• Wrist Detection appears to work because the Watch locks when I remove it from my wrist.
• Heart Rate measurement starts and the sensor lights turn on, but it fails to produce a reading.
• I have already checked the relevant settings and turned them off/on.
• I also performed a force restart, but the issue remains.

There was no obvious physical damage or change to how I was wearing the Watch. The problem appeared suddenly after it had been charging overnight.

Because this happened so suddenly, I am wondering whether a recent watchOS( 26.6 (23U67)) update or software issue could be responsible. The fact that the sensors appear to activate makes this even more confusing.

Has anyone with an Apple Watch SE 2 experienced the same issue recently? Is there a known watchOS bug affecting Raise to Wake, notification wake-up, and heart-rate readings at the same time?

I would really appreciate any troubleshooting suggestions before I unpair or reset the Watch.