Things just don't work...and then they do. Why?

I’ve had my SmartThings Starter Kit 3 nights. On the last two of them, around the same time things have just stopped working. Anything connected to the hub stops responding - sensors don’t show any update, plugs stop working etc. Yet those ones that can be controlled separately (such as some TP Link plugs) continue to work if controlled via Alexa etc.

Last night going into today things sorted themselves out at some point through no real intervention on my part. As I sat typing this, nothing was responsive. Logging into IDE suggested some of the sensors and hub were hunky dory, so I’ve just checked and I’ve got my 3rd party devices back and the multi-sensor, but the motion sensor (paired via a smartapp to a wall plug) isn’t working.

Are these gremlins something I can do something about? Or something I may even have caused?