faulty one Way Synchronisation

Hello,

My Vivosport receives all the data coming from Garmin Connect (Settings, ..) while synchronizing, but does not send any data to it. Steps, activities: Nothing is transmitted. This only works with USB cable on the PC. I've deleted the device several times from the Bluetooth list, reinstalled the app, ... All this brings nothing. When syncing, the bar that sync is completed will also turn green very quickly. Error messages are not shown. My phone seems to be connected perfectly. I also receive SMS messages and the weather from my mobile phone. Apparently, nothing is "sent" to the mobile phone. Can someone help me?
Isabel