AppleWatch keeps changing in my home wifi the private wifi configuration

I have in my peronsal Wifi MAC restricted devices access configured and so in my AppleWatch I have deactivated the private wifi configuration to ease the day to day manageement. This means that in Wifi wacth option (Deactivated/Fixed/Rotative) I set "deactivated" but after some days it changes alone to "fixed", hence the watch stops having Wifi access as the MAC adress changes from the one native (and allowed) by the router. Is this a known issue and fix exists?

It happens since some months in a Watch S8 in watchOS 11.3.1.

Thanks!