I am a green card holder and have had GE for about 1.5 years now.
Upon my last return to the USA a few weeks back, I tried to use the GE kiosk and had a problem. This was at BOS.
There are two types of kiosk. An older and a newer one. The newer one has a square glass area where you put your passport (green card, in my case) and it's supposed to read it. The older one has a gray/black slot that you slide your passport into.
The newer one did not work with my GC. I flagged down a CBP worker who was mulling around in the area and he tried to get my GC to work in the newer machine, also without success. He took me to the older style machine that worked instantly.
Anyone else experience this?