Cryptomatte by material seems weird. Need some help!

I tried to use cryptomatte by material, but in the pick output, they are not separate by material, most of it was combined in one single color. Here is the AO pass, and the pick output.
I want to pick the wall, but It’s black in pick output and I cannot select it.
I also want to pick bathtub but it’s green and it was not separate from other materials.
They all have different material and they should be separate properly. Any suggestions?

I am having the same problem. Some materials are black and can not be picked. Other materials share the same pick color-White. In the blend file the materials all have different names. So not sure why we are experiencing this.