Cadence?

I've noticed this a few times but never paid close enough attention to get details but I did this morning.  I uploaded my trainer workout (.fit file from Edge 500) and when the workout appeared in my training log, I see the typical metrics, time, speed, distance and the power numbers are blank.  However, there is an entry for cadence and it was set to 86.  When I click the link to edit the workout I don't see that 86 anywhere (cadence field is blank).  I then import the workout into GoldenCheetah to get the power details and it says that my cadence was 89.

I've definitely noticed it a few other times as well where the cadence entry that comes up is different than GC.

Edit: just to provide a 3rd data point, I also uploaded the workout to Garmin Connect and it says my cadence was 88.  So I guess it's a bit of an arbitrary number.  Still a bit odd that when I click the workout the cadence field is blank.

Edit #2: I just clicked on the workout again after having saved my changes and again, the cadence field is blank!