C4 disappear ???

I have seen this post in a forum on Facebook that discussed about this issue, but never through I would experience it myself after the update.

Today I played the map Contaminated. I was standing on the hill top at C. When I threw C4 onto a tank below, swear to god it did land on the tank. But right after that the C4 icon disappear.

Like what the hell??? I threw 3 C4 on that tank, but all was gone. Some how it did not stick on the tank anymore, clipped through it, and landed on the ground 😃. 

And tank's thermal smoke can disable C4??? What logic is this??? I threw the last C4 right after the first 3. Then the tank activate the smoke, the C4 was gone too.

Did EA intensionally nerf the C4 or this is some new bug?