Insert image in post not working

So this is what I’m trying to do on a portfolio-page:

1. Media -> Add Image
2. Select images
3. Insert into post

Everything’s fine until I press the “insert into post”-button. No images show up. So I try again and again, and it’s the same. The same problem are on regular pages as well. I’ve updated to WordPress 4.5 today, but this problem was the same in the last version. I don’t know how long it’s been like this, since I just got access to this website. I can add videos from Youtube, but not add actual images.

Can anyone help me identify what the problem is and possibly how to fix it? I’ve searched the web all day for a solution, but I haven’t found one.

Thank you!