Garmin connect - courses not saving

I'm trying to import a course from a.gpx file.

I open courses, select "import" and open the .gpx.

It all loads nicely and I see the course displayed on the map 

I select mountain biking as the course type

I click "Save" and a dialog box opens titled "Save course".

I check the course name and click "save" at the bottom of the box

Then nothing happens, save becomes blue/grey but that's it.

The course never saves and does not appear in my list of courses. 

I already have 150 courses, is there a limit? What else is stopping this from working??