Have you tried different pad placements?
Shifting the pads a little can make a big difference on the contraction.
Are you using it in long enough periods of time?
Yes, having someone take a look at your jumping and landing is an important part.
Going back and doing drill/skill work makes a big difference its about quality movement patterns.
Doesn’t sound like a mobility/strength issue.
Technique work is huge get video taped or watch a tape of a game.
Seeing it is key. You see exactly what is happening vs what you think is happening.
Its great.