Sonoff POWR2 no longer reporting as unavailable

Hi

I have been using a Home Assistant automation to notify me when the POWR2 became unavailable - this has been very successful up until a few days ago.

The Sonoff HACS integration appears to work fine and the device can be controlled by HASS - without problems

However the unavailable state is no longer working -
If the state goes to unavailable the POWR2 device in HASS continues to show as on, continues to show that it is drawing power and continues to show voltage etc. and the status does not change to unavailable.

I have reloaded the integration, deleted and readded the device but this does not seem to have helped.

I have also noticed that the device takes a while to move from on/off to unavailable in the SONOFF app as well - but even when it eventually does then this does not update in HASS
Any suggestions regarding this would be greatly appreciated.

Thanks
Neil