Very long rides are missing from import

I do randonneuring events and all my +600km rides are missing from the imported activities.
This year’s examples:

Try importing them using a different format.

I imported the fit files manually (tcx were too large).
Both 600k files returned an error like “2017-06-24-07-06-09 had an error during processing” after being successfully uploaded.
The +1000k files were too big to upload.