I'm trying to make a resource pack. I want to use overlay method to make powder snow look spreading, so I wrote a .properties file for it, but it doesn't work. The same .properties file works for snow block. I wonder if this is a bug, or I've made mistakes in the .properties file. The game version is 1.20.1, and mod version is 3.0.0 using connector 1.0.0 beta.46 in forge.
Here's my .properties file:

Non-full blocks cannot apply overlays; this is intended and works the same way in OptiFine. Changing this behavior breaks some existing packs, but I plan to add a new property to allow it in the future.

I see! Thank you for your reply. Looking forward to the next update :)