Apple Watch voice updates have stopped playing through AirPods

Voice updates from Apple Watch not coming through AirPods anymore.

I'm using an Apple Watch SE3 running OS26.3 and and iPhone 16 running iOS26.2.1

I use the watch to track my steps (and other health data) while out walking and listen to podcasts on the phone through Apple AirPods Pro earbuds.

Up to late January everything was working perfectly. The watch interrupted the podcast at every km mark to tell me my split time and then resumed the podcast automatically. There were also interruptions for "end of workout" or "move ring closed" etc. It was exactly what I wanted and I was very happy with it.

Then, suddenly the data updates from the watch stopped.

And, no matter what I do, I can't get them to work anymore.

What is happening now is the voice from the watch is coming out of the watch speaker and not through the AirPods - so, obviously I can't hear it when listening via earbuds.

I haven't changed anything - except, possibly, the watch has updated to the latest OS.

Can anyone help? Is there anything I can do to make it work the way it used to?

I have watched various YouTube tutorials and made various changes (toggle this or that setting on or off, unpair, re-pair, wifi on, wifi off, change Bluetooth settings etc etc) but nothing has worked.

Is this a change that Apple have made on purpose?

Thanks, Neil