Hi,
I had similar problems with my laptimer at Mugello last week too. Only this was a Solo 2 DL unit mounted in front of the tank.
Looking at the data, the positional accuracy was pretty good around almost all of the lap apart from on the main straight where the grandstand is.
My suspicion is that with the high grandstand, and possible further shrouding as I was leaning forward to get out of the wind blast, meant the unit couldn’t detect the finish line and hence wasn’t registering laps. Luckily, it looks like the analysis software has resolved this.
Seems these units are very sensitive to not seeing the multiple satellites particularly when going over a finish line. Hence, I was seeing no laptimes.
As you say, Alex, positioning is crucial.