Like you my issues usually happened at relatively low speeds (though once at about 25kph), both in first gear and reverse. The technicians explained that the error code they received should only appear after a substantial collision so something was obviously amiss.
The warning message and steering failure happened simultaneously in each case.
I was hoping that a change of software would be the answer as I wasn't keen to add to landfill, but Ford felt that a new steering rack was the safest most reliable solution.
1000km later and I haven't had a any issues (touch wood).
Good luck :-)