Syncing Multiple Google Classrooms with one Khan Academy class

I want to compile all my students into one Khan Academy page to make it easier to push out assignments, but I have them in multiple different Google Classrooms divided by section. When I try to add multiple Google Classrooms to the same Khan Academy class, it only lets me sync one Google Classroom. I keep getting an error message when I try to add more. 

Is there a reason this is happening? Does anyone have a workaround?