iPhone cannot deactivate Apple Watch Flight Mode

Hello,

I have an iPhone 17 Pro paired with an Apple Watch Series 11. For several weeks now, mirroring has not been working in flight mode. Bluetooth is enabled on both devices (the iPhone indicates that the watch is connected properly).

My problem is that when I activate flight mode on my iPhone or watch, it is activated on both devices, but the reverse does not work: when I deactivate flight mode on my iPhone or watch, it is not deactivated on the other device.

When I try to do this, I get the following message: "The iPhone could not deactivate flight mode on the Apple Watch" .

I have tried disabling and re-enabling iPhone mirroring on the watch. This did not change anything.

Both devices are up to date: iOS 26.3

I must emphasise that it worked before and I have not changed any settings since then.

Thank you very much for your advice.