There's more to it than that - my iPhone is on 13.5.1 and it can receive notifications just fine. My other phone is an Android (Google Pixel) and I can receive notifications there as well.
OK thanks. I'm in the public beta stream for iOS, so I have no clue what the current release version is. Is it 13.5.1 for iPad or is that a beta build for iOS on iPad (which I thought was the same for iPhone, but I'm not certain about that).
Leaving you iPad at 13.5.1, can you please try deleting the Hubitat app and reinstalling it on your iPad?
@jared.zimmerman Could you please let us know what version of iOS you are running on the device that is not receiving notifications, and the version of the Hubitat App.
Next, please try removing and reinstalling the Hubitat app and let us know if that also resolves the issue for you as it did for @Brandon.