Just for the record, yesterday I had another occasion of the phone not charging, with the state remaining "discharging", although the cable was connected and live and the charge level was below the discharge limit. After reboot, charging restarted.
The most obvious difference to the earlier behaviour, by the way, is also a slight improvement: While earlier a failure to charge (along with entering the "not charging" mode) still showed a battery plus flash symbol in the status area as if it was charging, now the flash doesn't even appear, so I can at least see that it doesn't charge without