Dear Garmin support team.
Two days ago I observed that many of my activities uploaded to Garmin Connect have lost the GPS track data and also had trouble with the edition feature, at least from the main activity page.
Then yesterday I uploaded a new activity, showed fine, but after some editing, It started behaving in the same way. The curious thing is that if you look to the data from the 'dashboard' you can see the GPS data, but not if you enter the activity. As a software engineer, and having not experienced this before, I suspected that may be a new bug introduced with the latest changes in your software.
I tried to reproduce the steps that lead to the activity messing and I finally found out the problem: In some of them, I'm using the " symbol (that represents seconds) in order to keep track of my running interval times. For example 1000m in 3'28" lap. The moment I introduced the symbol, the activity started behaving weird. I tried to remove it and then things came back to normal and I recovered the track data and editing capabilities.
As the " is a special symbol used in HTML programming that escapes name data, I guess you might have a problem parsing the data activity that leads into wrong behaviour.
I think this is pretty critical because many people may be experiencing the same problem. I also think that should be pretty easy to fix, so I hope you can have a loot at it. By the moment, I'm not using the special char on my trainings until fixed.
Keep up with the good work and working with new Garmin Connect features ;)