The compiler gives a wrong (or at least misleading or partial) error message when using anything from Toybox.ActivityRecording:
Permission 'Fit' required for '$.Toybox.ActivityRecording'.
However I already have the "FIT Contributor" permission checked in the manifest editor, and what actually is missing is the "Activity Recording".
IMHO the confusion is because the permissions are called differently in the manifest XML, in the manifest Editor and in the error message. For example:
xml: Fit
error message: Fit
editor: Activity Recording
Recommended possible fixes:
1. change the text in the manifest editor to include the xml value of the permission, i.e: "Activity Recording (Fit)"
2. change the error message to include the permission name as it is displayed in the manifest editor, i.e: "Permission 'Fit' (Activity Recording) required for '$.Toybox.ActivityRecording'."