Generic rig creates sliding feet?

Hello guys, I would really appreciate your help. So, I imported a rig and animation. I choose 'Generic' as animation type and set the 'Root node' to the world joint of the rig. I add the rig to the scene and press play and the animation doesn't play properly. The feet are sliding or floating or sometimes moves jerky. I tried to choose humanoid and the feet were staying on the ground. The problem is that I CAN'T use humanoid since the animation have squash and stretch.

Why isn't the generic system working properly? I tried choosing bake into pose and every setting. Nothing works. The feet won't stay in place. It feels like there is something wrong but the 'root node' maybe? Any ideas how I can solve this?

(I also tried turning of root motion and turning off/on foot IK)