The PDF debugger doesn't print correctly inline images in content stream, unfiltered view. It actually prints only the BI operator, no parameters, no image data. I'm attaching a screenshot where you can see the difference from the debugger and printing the the stream to sysout.
Also, looking at the code, the panel prints the parsed tokens (I'm looking at StreamPane::getContentStreamDocument). I find it a little confusing because the combo box says "unfiltered" so I was expecting the raw, unfiltered stream data, not the result of the PDFBox stream parsing.
Side note, it would be nice to be able to select and copy (ctrl-c) the content from the stream panel.