I have a running activity, recorded with Forerunner 35. It was recorded during a duathlon race.
When I try to convert it to multisport activity (either with mobile, either with web app), I am allowed to define the duration of the first leg and to select the type of second leg. But when it comes to saving the change, the app throws an error, saying "An error occurred at our side. Please try to save this activity again."
This was working before new-look GUI was launched.