D’oh! Sure enough, there it is! I don’t know what I have misconfigured, but for some reason github doesn’t notify me by e-mail when someone opens an issue in my repo. I get e-mail notifications for other things, but not that. Argh!! And when I’ve looked recently, I didn’t notice it because github didn’t mark it as new either.
Anyway, thanks. I’ll look at the unifi code, but clearly it is putting a timestamp in the last_seen attribute instead of a datetime like Google Maps Location Sharing and my Life360 trackers do. I suppose an issue against the unifi component could be opened asking for it to be changed to a timezone aware datetime in UTC (which might be a breaking change), or I could look at changing my code to try it as a timestamp if there’s an exception using it as a datetime.