Had this issue. Filled the tank to the brim, then immediately had 650mi until no start…the day before I had to make a 640mi round trip up north. The last 20mi home was squeaky bum time I can tell you.
In the end, I’ve had a guy “map out” the “no restart” function from the main ECU. Gets rid of the panic over no restart, just leaves the fault in place. Not bothering to have it fixed as the car is fine with the fault in place. Will wait for Audi to issue a recall to fix the, clearly common, fault. I’m guessing I’ve got more chance of !Removed! from a rocking horse than a recall, but let’s see!
If anyone’s interested, the guy is Andy at https://ecuflash.co