Unable to add Background Image - Forum - iMOD

I am fairly new to the program, so this might be a simple error. Every time I try to add a background image to my iMOD project via the view menu, I get the error saying the file I want to upload is missing. I have tried both PNG and JPG files, both gave the same error. I cannot get my head around this, since the 'Island.PNG' image from the tutorial folder worked when I first started the program and is still working when I try adding that image now. Also, when I place or copy my own image to the tutorial folder, the error remains the same. What is wrong with my own images which leads to iMOD refusing to read and add them?
For the full picture: I use iMOD version 4.4 in Windows 10. The images I want to use are now in PNG and JPG formats. I have changed nothing in the IMOD_INIT.prf file after installing.