Your screen shots showing the sprint markers indicate your route covered 18.2-1.8=16.4 km (10.2 miles) or a bit more, from the first to the second sprint marker crossing.
Are you saying that riding from the sprint marker and back is actually the 10.04 miles shown in Strava?
Ok, so this is what I have: Starting from that marker on Tempus Fugit and coming back to it is 10 miles and confirmed this afternoon by Zwift support 
The segment I set up on Strava is near as I can get it because of the way Strava does not provide an overlay map when creating segments in Zwift. My Tip would still to give it the biscuits at the start and maybe stop to puke at the fork in the road to ensure youve hit the ZSUN TT. Good luck 
I see you got it right at 16.09 nice.
Mine kept coming up as 16.07 or 16.11 so I left it at 16.11
I use a reference marker to make segments.
What was your time for the ten miles?
To whom asked, Strava deleted a vast array of former segments. It can only be personal segments now.