Well, zwiftpower typically shows a “lag” in the TTT results until it has processed the fit file. So I’m not convinced that this lag is the cause of the issue, maybe it’s more an indicator of whether it used live data or a fit file (just like the green and blue bolts).
Yesterday we did an experiment in my team. We had a start delay of 12.5 minutes. So I told the others that after we cross the finish line, we continue riding for some minutes and finish at about 11, 12, 13, 14 and 15 minutes and afterwards check if we find any correlation between the fit file analysis and whether we did less or more than the start delay.
But it failed:
Finish time 41:30, distance was 27.5 km
Gary - 28.4 km - 46:04 = green (his headset didn’t work so he couldn’t hear my suggestion on riding longer…)
Ryan - 33.3 km - 53:04 = green
Andy - 35.1 km - 54:17 = green
Mario - 31.5 km - 54:37 = green
Anders - 33.2 km - 57:21 = green
Timmy - 34.3 km - 57:23 = green
Dave - 32.7 km - 58:06 = green
So even if we rode a few kilometers extra and rode for up to 16 minutes after the finish line, none of us got the file processed. A lot more than our start delay. Weird!
I noticed that in the team finishing right after us, Herd of Lions, 4 of 8 had a blue bolt. Their start delay was 8.5min, I believe, and among those who got the blue bolt, the guy who rode shortest time did about 12min after the finish banner.
After all…now I’ve feel I’ve lost a clue about how and why this happens - but I believe we know for sure that continuing to ride for a good while after the TTT will increase the chance of having the fit file processed in the end.