imshow in app designer is not working

I am trying to show the first frame of a video on a gui in app designer. So far, everything seems to process, and I am not receiving any errors, but the image I want is not showing. All I get is the UIAxes disapears, and nothing shows up.

obj=VideoReader(x); vid=read(obj); firstframe=read(obj,1); imshow(firstframe,'Parent',app.UIAxes);