Instinct Solar Activitis disapear in Explore Web and Phone

Is it possible to manually import a Garmin Activity FIT file from the Solar to Garmin Explore? On the Phone the today activity was synced but dont with the explore Website. After i reconnected the Phone App the today Activity was gone from everywhere. After new sync of the Solar the Activity dont apear anymore. In the Activityfolder on the Solar the Fite file still exists! Are there any sugestions what i made wrong?