Indeed matey - the 'quick capture', by clicking it once on top from 'off'.
Perhaps I'm safer to use the capture function through the menu with it already powered on, then? I've had this a couple of times now on my last Ring trip and the lads who weren't so experienced with it also had the same issue, so it might be a fat finger/delayed press situation
Ooops
Good point re. the card, I'll check. I've got a few I can swap it around for so will see if it's a class 10
Thanks for explanation, seems likely