Unable to add Zipato Indoor Siren PH-PSE02-1B-EU to the Hub

Hi there,
I’ve had two Zipato indoor sirens perfectly working with my smartthings system for the past two years.
Suddenly one of them became for no reasons unavailable 10 days ago and ever since it has been impossible for me to have it working once again.
Moreover, following smartthings support instructions I tried to remove it from the system and while doing so the other zipato siren became unavailable too. I got them successfully removed from smartthings system but now there is no way to have them recognised and re added to the Hub.
At some point I thought they were broken…I purchased two new zipato indoor system, but the result is still the same…no way to pair them to the hub…any help please?

Thanks,
Ludo

Which device handler are you using?