Thanks for the link, though only “check database” may potentially be of help. I’ve done that now, and I’ll have to see whether the issue reoccurs the next time I lapse a card.
However, some cards don’t appear to have this issue and I have a suspicion that it only occurs with cards that were created before I set the deck’s New Interval to 22% (from 0%), which are most of my cards.
Even if your cards were created before, it should work if you’re using the right settings in the right deck. If you’re using subdecks, I would check that all of them are using the same “new interval” setting.