Import swim workout FIT files?

I am trying to export training peaks structured swim workout files (uncompleted) and IMPORT them into interval.icu.

They are .fit files.

I always get this error : Unsupported file type: application/octet-stream

What platform are you doing the import on?

I’m not sure I understand the question. In Interval.icu → Add calendar entry → Swim → Upload Attachment

I just did that with the file you sent me and it worked fine. I meant what operating system and browser are you using?

Thanks for answer. System : Mac
Browser: Originally Chrome but just tried with Safari and Firefox and get the same error.

Thanks in advance

Aha. That last bit should be “Import”: