alpha z buffer

Hi, I want to create a soft alpha shader that writes to the z buffer. I use your Clip and Transmission shader for this, first I disconnect the alpha from the Alpha Clip input in the Main node and put it in the Alpha input above it. Next I uncheck the Auto-sort box and check the Write to Z Buffer box. I believe this is the way to create a soft alpha with depth sorting?

The problem now is a is a bit hard to explain but from some view angles(I look at the plant in the example scene) when 2 or more leafs overlap the leaf that's at the back is masked by the whole polygon not just the alpha. While the floor behind it is rendered correct. I hope you understand what I mean;)

This is fixed when I connect both the alpha and the alpa clip inputs.

I dont't know if it is a bug or the only way to use an alpha with z buffer?