moving a planned workout not working

I keep trying to move Monday's bike to today.  I thought I had done it at the beginning of the week but then I got my email and only a swim.  So I just tried 3 more times.  In the Planned Calendar view I drag the workout over to Wed and it shows up there, but as soon as I navigate away it's gone.  The swim that is on the schedule was also moved from Monday and it sticks.  I am using Firefox