Hmmm....

Not sure what's going on, but I stopped getting any notifications at all so tried rebooting the phone and now it seems to be working OK. I think most of the blank notifications were from my gmail account, and interestingly there are now two notification classes labelled 'gmail' and two labelled 'SMS' in Rockpool's notifications menu.

It literally just said [Action] (once twice, once three times - both times followed by 'Start quiet time'). I selected [Action] once and it said 'Success', but goodness only knows what it did

I'll have a fiddle with it, see if I can make it do it again, but as I said as of this minute it seems to be behaving correctly.