xlsx-files upload will save as bin-files

When I upload a xlsx-file with the media upload, the file will be saved in the hmc as a .bin-file. I have tried to upload csv, docx and xls files. All these file extensions works well, only xlsx-files will upload as bin-files. At the moment im using the hybris version 6.2.

Has anyone already had this problem or know how to fix it?