When do you get a negative lap distance? Before/during leaving the pits? Every time? Does it happen during pit stops?
That would seem to make some sense. When the race starts everyone is technically in the race, but if you have the guy in last at 2500m and the leader is at 2m, it could be a bit confusing if you're relying on those numbers and it looks like the guy in last is ahead. I only had a quick look at a couple of logs and saw negatives when leaving the pits after first jumping in the car. Seems to make some sense for the same reason.
I am just confused how to interpret that value during a race session as I'm seeing th value raising during the lap until it suddenly gets below 0