I ran into a small bug, I'm not sure I'm doing everything right, but premultiplied alpha blending (One OneMinusSrcAlpha) throws this warning: "Opacity is connected, but your shader isn't alpha blended, which is required by the fade transparency mode. Click the icon to make it alpha blended!" , even though it is an alpha blended transfer mode.
It should essentially be alpha blended at 1.0 alpha value and "lerped" to additive transfer mode at 0.0 alpha, which means it shouldn't throw this warning.
It's more of a minor annoyance really, i hope i'm right about this and to report this as a bug.
Customer support service by UserEcho