I use Anki 2.0.82 on iPhone, with the v3 scheduler.
Here are the steps to reproduce a bug that I notice quite regularly.
- During a review, tap the gear icon on the bottom right and set a flag on the current card.
- Answer the current card.
- On the next card, tap the gear icon on the bottom right and select undo answer.
- It still displays the new card, it does not go back to the previous card (this is the bug).
- If you tap the gear again, you can undo the flag.
- Now it shows the previous card.
I can’t be sure that this isn’t the intended behavior of course, but it does seem counterintuitive every single time it happens.