I get this regularly, even as recently as a few days ago (see vid, right at the end. I come 2nd by about 3s but get credited with a huge win by 1m:48s). It's like the leader and everyone else missed a lap in the final calculation but weren't missing a lap by the live timing during the race. That sounds like a simple bug to fix to me. Seeing as I nearly always do private league racing it's not a problem. I can't see a pattern to it but it must be massively frustrating for public lobby racing.
btw I was the host for that race so that may have something to do with it. Watching the race leaderboard closely should be good test data for SMS.