Play/Pause not working with Bluetooth headphones on iPhone

If I press the play/pause button on my Bluetooth headphones the music stops as expected but it does not resume when pressing the button again.
This also happens when using Siri: The music pauses but it does not resume.
To resume playing I need to use the Roon app.

I’ve tried this with 3 different headphones and the issue occurs with all of them.
I don’t have this issue with other music apps such as Tidal or Apple Music.

Any ideas?
Thanks.

iPhone 13, OS 15.2.1