Hello, the tire maybe stuck to the under coating on the frame, try to gently pry the tire away from the frame and then try lowering it again. The spare tire hoist needs the weight of the tire on it to lower . Try that and let me know if it worked.
I see your expert is off line, so to lower the spare tire carrier, give the cable some slack, and go under the truck, lift the rubber boot and you will see the secondary latch. To release it, you can push on the center piece to release it. You will understand more when you are looking at the mechanism. Please ask if you need more details.