The problem you are experiencing is the gas blow back that is amplified because of the suppressor retaining more gasses and directing them into your chamber. Verdigris, is what you are seeing on your brass after you leave it in the chamber, since the gasses are amplified they cause corrosion on the case, maybe it takes overnight, I've seen it in a matter of 30 minutes.
To fix this problem, you will need to clear the chamber ASAP after shooting, or get an adjustable gas block that will decrease the pressure and returned gasses caused by the can. You can also go with a piston driven system that will eliminate the problem.
I run my AR's dry, or use a dry lube, oil based lubes will mix and become very very dirty/sticky, and could even cause excessive pressure if it's not properly cleaned from the chamber. In my location the oil viscosity changes too much in the cold weather and I see additional issues, which is another reason I prefer dry lube.
I would also look into a SB sizer die, on any AR platform when the webbing expands you get sticky cases, and when you run a suppressor that's direct impingement the problems multiply because of dirty gasses. I've gotten away with a lot less problems and cleaner cycling by small base sizing my brass when using an AR platform.
