I often leave the driver door open when hitching up tp a trailer. The Grenadier won't let you. It shifts into neutral when you start backwards with the door open.I tried to back on to a trailer yesterday and it kept locking my brakes. I disabled everything. Nothing worked. I pulled forward and tried again - it went on like butter. I have no idea. I did nothing to fix it other than try again.
I found a hack. Two-foot the pedals. Keep the brake slightly depressed until moving backwards. Then it won't shift out of reverse.