Apologies if this is already an opepn bug, but it's an issue that won't stop happening for me. I've got a kanji helper schedule (Kanji for 初中級の単語) and recently one kanji's onyomi vector kept coming up up for revision even through I answered the question right, then two and now three. Oddly enough eventhough the terms never register as revised the study streak on the schedule is not affected.