Ember Table (V1.13.1), extra column or table not filling the width of the table wrapper

Worth noting, I just began working with Ember a couple of days ago, so I dont have experience. I am maintaining a system (using ember 1.13.1) and there is a table with 7 columns defined in one of the pages (No, Attached File, Source Format, Export Format, Size, Type, Status). Any suggestions what might cause this problem?

Finally, can you give me some advice on how I can go about to learn Ember?

Best regards