Race Past Activity Not Working?

I used the race past activity feature on the Instinct a few times and it worked 100%.  It would tell me if I was eg 5 seconds ahead or 10 seconds behind compared to my previous run.  Now it seems to not work at all.  Within 5 seconds or so of starting an activity it jumps to showing that I am 1min30 seconds behind which is absolutely impossible.  I have tested it again and again and the same problem appears again and again.  Any advice or solution to this?