"Ultimamente não."

Translation: Not lately.

[D9876]

Could this be Lately No as well?

[margaritaguese]

Right, that answer should be accepted. I would also argue that lately not is not even grammatically correct but that's just the teacher in me. Make sure you report this!

[-HKBK-]

Both ´lately no´, and ´lately not´ don´t sound right at all. Duolingo´s translation of putting ´not lately´ seems to be the best option.

[HelBald]

I agree, 'not lately' sounds better. But 'lately, no' is accepted and I can perhaps imagine saying it in a conversation. 'Have you been going to your exercise class?' "Lately, no." to emphasise that it's only lately that I've not attended.