Issue with Rolling Pace

Every now and then when I'm out for a run, my rolling pace will mess up. I will hit a km, the split will pop up on my watch (say 5:10/km, for example). Then, I'll maintain my pace, and when I look down at my rolling pace it will be counting up from 5:10 and it will continue counting as if it is a stopwatch, so by the time I finish my next km, it shows a rolling pace of 10:20, then 15:30 by the end of my 3rd km. This will continue for the entirety of the run so although my splits still pop up, my rolling pace doesn't show between splits, which makes it very hard if I'm trying to run a certain pace during certain kms. Has anyone else had this issue?