I don't know whether this has occurred with anyone else but this seriously pissed me off.
A friend and I found 2 other players on a LFG and we played trials trying to go flawless. We were doing pretty well and made it 6-0 (my friend had to go for 20 mins after our 5th win so we played some crucible while we waited) so we were pumped for our final game. The game ended and we won 6-2 but in the bottom corner where it displays your current trials passage it came up with 6 wins despite already on 6 wins prior to the match. This was pretty annoying but we didn't mind playing another game. But when I went to launch trials again, the passage then said I had 6 wins and 1 loss. This was the same for 3 of us except one person who managed to go flawless. I don't know whether this was just a one off glitch that's only happened to us but it definitely pissed us off. I doubt anything can be done about this now but I feel like people should be aware of this bug anyway.
I've linked my DTR to prove that the past 7 Trials of the Nine matches were wins (ignore the loss in countdown and game in clash like I mentioned earlier as they are just regular crucible games).
http://destinytracker.com/d2/profile/psn/Its_Jack02
Destiny Trials Report also confirms that I have gone flawless once and I have won 7 games in a row.
https://destinytrialsreport.com/report/ps/Its_Jack02
Image of my current trials passage
https://imgur.com/a/6PN1i
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DTR considers Trials matches to be Countdown matches. That DTR record doesn't prove anything really, we have no clue wether or not that match was actually Trials. Now considering you has the same fireteam for that match as you did the rest and your friend apparently had to leave. This doesn't add up, it looks like you got 6-1 in trials from your record