Searching the forums for "cadence graph" will show you that you are not the only person with this problem. The only known solution is to edit your activity and change the activity type to one of the top-level activity types (Running or Cycling work fine, but Trail Running and Road Cycling do not).
I am having this same problem, and it is affecting all cadence data, including the years of historical data I have loaded up in GC It is an unacceptable solution to go back in and have to change the category to get it to appear. I use the categories specifically to categorize my rides to keep track of different types of mileage for different types of bikes, ride types, races, etc. 700 + cycling activities since July 2007 makes that a ridiculous fools errand to reclassify. I guess it's time to find another program to keep all this tracked in.
I have also noted that ALL my "street running" activities have lost all cadence data. Ran the treadmill the other day and had the same issue. Forerunner 220, latest updated software. After changing the last entry to RUNNING, the cadence data returned. As a previous poster mentioned, it's a bit much to have to go back and change the type of event just to see the cadence of a previous event. Please remedy this.
It shows the quality of the software developers working for Garmin as they are not able to solve this issue within 2 weeks (or even more) since it was discovered... Strava does show the cadence data by the way. I'm using that together with some friends that do not own a Garmin device.
Bloody hell, I have to say that for a free service it's pretty damn good. They'll fix it its in there interests, there are always some issues with a major rev...
