What is going on with SSJ4 Vegeta's kick? Why is it so unreliable???

When you land your kick on an opponent, and they hit a wall, they are supposed to be staggered, correct? Am I getting that right? Apparently not because it doesn't happen.

This isn't just a coincidence that happens once in a blue moon, every single match I have had with him, his skill 2 has a SLIGHT chance of actually staggering the enemy.

The first few times I chalked it off to maybe using the kick at an off angle or "that wall/terrain just doesn't count for some reason". But no, this is in every match now. I only try to kick the enemy directly 180 degrees with the wall to their backs. Doesn't work. His kick will not stun majority of the time I land it on an enemy and they hit a wall. They act like nothing happened and I'm flabbergasted at this and can't understand why.

I was just in a match where I kicked the enemy Vegeta into a wall, he slid off like it was nothing. A few seconds later after rush attacking we're in opposite positions, he kicks me into the same exact wall, same position, same direction, and I get staggered.

?????????????????

I'm genuinely lost here. What is going on? Am I just somehow not using it right? I'm looking at videos, reading the ability, but nope. There is nothing.

I can't enjoy using this character at all because his best move's CC refuses to activate 80% of the time.