I played Zyra with the Wildfire Skin and the the Plants of her Q didn't attack. They only stood there untill they were killed/died.
I haven't tested it without the skin yet, so I don't know if this also happens when she has her normal skin.

Her q make the plants that are ranged.. Were they close enough to the target?
Was it a ranged target and they out-ranged the plants?

yep, her plants of her q didnt work

Her Q attacks seem really buggy as of late. Sometimes they attack sometimes they don't and this is on live...

Agreed, I see them delay a lot between attacks on live...

I have been told that this problem is only present with Wildfire Zyra.

Also, I think it affects vinelashers too. Not just the thornspitters.

Saw this happen in the past 2 games. A Zyra with no skin had no problems with the Q plants, worked as intended. Whereas in the next game a Zyra with the Wildfire skin had the Q plants show up on the map but they didn't attack anything. Hope this gets fixed soon. Until then I guess people will just have to play Zyra without her skin.