Cannot change image after node has been saved

Hi all,

I'm using:

* IMCE 6.x-1.2
* IMCE Wysiwyg API bridge 6.x-1.0
* WSYWIG 6.x-2.0

I can upload an image and send it to the editor. I can change it as well, without any problems.

However, when I save my node (or preview it) I cannot change the image anymore. When I select the image and press the 'Insert/edit image' button, nothing happens. If I deselect the image (by placing my pointer in a the text of the node) the 'Insert/edit image' button is behaving normally.

Is there anything that could cause this behaviour?
We have a go-live tomorrow, so any help on this issue is greatly appreciated!