Shuji at Zwift HQ here. Looked through your server logs for clues, and I found you’re using Zwift on a Windows PC.
If your Polar H10 is using their firmware version 4.1.10 or newer - those versions comply with an EU regulation for data privacy. With Windows - this means you’ll want to pair the HRM as a Bluetooth device at the OS level, like you might for a Bluetooth mouse or earbuds.
Note: this is a separate thing than the HRM consent popup that Zwift introduced in game version 1.111. That’s covered in the release note thread: