HRM Pro Plus does not appear in the activities

Hey community, please help me.
So far, my watch and HRM have been shown as devices used in my activities. For some time now, the HRM is no longer displayed in the activities.
I have to download the heart rate data manually after each activity.
The HRM is connected to the app, it is connected to the watch (Fenix 3 HR), the app shows that the HRM has been synchronized. And yet the information from the HRM is not assigned to the activity (at least not automatically).
I have reinstalled both the watch and the HRM on the app, etc.
What can I do?
Many thanks and best regards

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