You're right. It was reduced to 0 height.
Some other issues:
- It needs a minimum height. I just reduced it to "below 0" size by dragging horizontal column browser below it up to the caption bar. Now I can't resize artist picture element anymore. (I found a way to recover it. Remove the element from the main panel, exit, run v3.0, exit, and then run v3.1 again)
- The order of elements matters. Try column browser/thumbnail browser/artist picture/files order for the main panel and you will see it breaks the UI.
- Maybe some elements (or some layouts) shouldn't be allowed to be placed in the main panel along with artist picture element to make things simpler.