How do you import .png files (such as favorite channels, or background designs) into CCP for the MX-990?

I can import the .png file into the MX-980 simulator by clicking in the "image" box and then selecting "import", but those same steps won't import the same .png file into the MX-990 simulator. What am I doing wrong in the MX-990 simulator?

I have a MX-990 remote so I would much rather use the MX-990 simulator than the MX-980 simulator in CCP.

Thanks to all the experts who take the time to respond!