I had the same problem with my Zodiac G3 and Great White. They would both end up stuck on the main drain. The problem was a suction balance between the floor drain and skimmer. Too little suction on the floor drain created too much suction on the skimmer powered G3. The way my pool was constructed I am not able to shut the main drain off completely. I finally found a very simple fix. I took the PVC connection from the tailpipe of a sink drain to the trap and put it between the G3 and hose. I drilled holes in this section (about 8 1/8 inch holes) one at a time until I got the right balance of suction. The Zodiac Baracuda Cleaner Automatic Flow Keeper Control Valve that came with the G3 kept breaking the springs, probably because our pool is salt and at $40 a shot I didn’t want to keep buying new ones. This simple solution fixed the problem and my cleaner no longer hangs up on the floor drain. Also, no moving parts to break... Good luck.
