Content over the slide is not showing up at all

I cannot get any content to show up over the slide. The slides themselves work fine, but I need a logo over them (it’s a .png) each slide and have tried the “Add Media” function to place the logo in the text/content field in the “Slide Info” tab, but the preview doesn’t show anything at all. I even tried just just typing plain text to see if anything will show up, but nothing there either.

Would you pls help?