Turning on Alpha channel support for post processing in UE4 causes issues with cineCamera actor

I’m trying to use the composure plugin to create composite images for my UE4.27 project. As given in the docs for the plugin I’ve turned on alpha channel support for post processing in project settings as well as used a cinecamera actor as the source. But I am getting weird issues with cinecamera actor when I increase post-processing blend weight.