Your comments

Just run into the same problem, bummer there's no real work around

Ah I take it back, Unity was saying it was rendering a depth texture for the camera when It wasn't, indeed not a bug
hmm it is deffered and as in the top picture it does have a depth texture, until it doesn't for some reason
Hmm actually I take that back I still can't seem to access the depth channel, everything else is fine but trying to use the MainTex's alpha channel or the depth node seems to get zero results, this is definitely the shader
Yea I'm not sure what's wrong but as soon as I tried to record this the problem went away without me changing anything... typical, thanks for the help
Right, super peculiar development, if the material is applied to a mesh it's fine, compiles and works as a material and post process effect. As soon as no mesh in the scene has this material applied to it goes back to compiling to all black
Really strange, I tried on my work computer and it had no issue with it

I'll try recreating it at home later