Terrain detail mesh sliding on floor instead of bending (video of the problem)


I am attempting to add a few detail meshes made by me. I need them to be affected by wind (same as grass). The problem is that the meshes slide on the ground instead of bending like the grass around the pivot point. In render mode I have Grass selected (because I also need transparency).

Video of the problem: This is a problem that I did not find an answer to on the forums or Google, and I don't have time to wait days for an answer on Unity Answers. I want to... | By Endi | Facebook

Please help.

The tree creator will ensure the wind effect.

The answer is over here:

Need to paint the vertices alpha.