Assisted braking is partly broken (really, really broken)

I just tried to do the monster truck exhibition with assisted braking on. Now I know it is not great for competitive racing, though there it seems better than FH4 where it’s heavily nerfed. I got through the race and came second, which isn’t the problem.

The problem was the next bit. The car did not move. Almost literally. Reverse was fine but forward movement was what, 1 mph? Not an under-estimate, the car barely moved. I’ve noticed this occuring when in a race or free roam I attempt to drive some way off the route if one is set. That I can sort-of see but don’t really get completely, but in the second bit of that exhibition there is no route. I knocked over 17 pins in reverse before realising how stupid I was being and stopped.

I’ll do it again with ABS, presumably it’ll be fine so it’s not like there’s no workaround. That stated, it surely shouldn’t be THAT bad, right?