It would be an overhang problem. You could change the channel to a 45 degree notch. But it wouldn’t hold the photo as secure.

Simplest might be to fill in more of the back so you don’t have that thin rectangle going up high until it meets the other rectangle in the middle. Thickening those parts would also help. The back frame could be changed to a hollow square cross section. That would make it stable without significant material.