Nope, that fixes it. I suppose that means one of my Community Plugins is the source of the problem …
… or perhaps “was” the problem, since turning off safe mode and restarting obsidian has not (so far) caused the problem to recur, but if it does, I now know what to do, i.e. turn them off and back on individually until the culprit owns up
I also discovered as a result of this that about a dozen plugins needed updating, which may well have been contributing
Many thanks for your help!