Zyra buff and E problems

I've been playing Zyra a lot lately and I noticed two things:

1. Her Grasping roots (E) wont appear once in a while when I cast the spell. It goes on cooldown but it's like the animation don't go off, nor does the dmg and the root.

2)The second problem happened to me 3 time in my last 4 game. I had the blue and red buff animation without truly having the buff. My teamates told me they could see me with the buff, but I had none of the buff effects, and it stayed on me till the end of the game even if I died. So in the end it was confusing to know if I realy had the buff. I think it might happen when you kill someone with zyra's passive but I'm not sure.