uploading images does not work on safari

Hello All,

Hope you can help me, been struggling with this for a week now.

When I try to upload images into my media library working from my mac, it doesn't work. I just see a gray line where it hangs, I get no error message.
When I log in from my windowslaptop, same account, same internet connection, it works without problems.

How is this possible ? Last week it worked on and of on Safari, this week I have not been able to upload any picture at all from my mac. Problem is that all my pictures are on here.

Thanks for any advice you can give !

Lianne