If they are not ejecting at all it means you are getting insufficient gas. Weird stove pipes malfunctions would be your bcg is moving to fast, meaning to much gas. Probably misaligned gas block or an issue from the factory with the port size not being drilled out enough or a gas tube not being to spec or misaligned. It's rare to be that under gassed with a suppressor...your getting what I get when I turn my adjustable gas block all the way closed, meaning no gas coming back into the system.
I would check gas back alignment as OP said. Springco does sell a yellow spring that is lighter than a standard buffer spring, you can also get a lightweight buffer and or bcg if really needed, but that shouldn't be necessary. Check to make sure everything is in alignment and(funny to say) everything was drilled out properly.