I don't know if this is a specific problem with the way I'm inserting images or if it an actual bug atm, but for some reason I literally cannot add images to my profile.
When I try and insert them from the insert image button, I can select and browse images fine, but when I press insert, nothing comes up on the profile.

It's just limited to my profile, my feed is absolutely fine. And I can add gifs so long as I put a link address in. Also can't add them through the normal browse / insert function.

Anyone got any idea what I'm doing wrong?

Same thing is happening to me except I tried adding some different images and they work, maybe it's something to do with the size of the image?
It is the visual editor, for some reason. Open up the html editor instead. I explained in more detail how to do it in the other thread. (^_^)
You gave me an idea...I was having exactly the same problem.  So, I opened my jpg file up in Paint and saved it as a .png file.  I tried uploading that and it worked just fine.  problem solved for me!