Image insertion in Rich text not working

I needed to wrap text around a box for a new project, so I tried using rich text.
I realise that this doesn't work for a floating element such as a box, so I planned to use a transparent image for the text to wrap around and then place the box over the top of it.
Seems fine in theory, but unfortunately when I try to insert an image into the rich text element it goes as far as sending me to the image browser to select the image, but then doesn't insert anything!
This seems like a simple task that doesn't appear to be working. Hence the bug report.
Could you look into this ASAP, please, as my client is waiting.