To check, just lifting myself up off the seat and releasing the belts revealed what was going on.
I know your not supposed to modify belts but . With a file i extended the slot in the crutch strap buckle about 4mm towards the belt and rounded all edges.
In my first post i said lap belt cocked sideways but i meant crutch belt.
A few years ago at Glenroy Plains we were first on the scene to a buggy on it's roof. The driver managed to get out but the navi who was a big guy tried to release his belt and broke the release latch on the lever latch belt and it failed to release. We tried pliers and screwdriver in the latch but no go. We then tried to cut the belts with mixed success. Using a rusty pocket knife near a man's testicles has its risks. It wasn't till more cars stopped and we could lift it over on its wheels that the belt released. This was pre-cutters and the belts were brand new before he event.