If you uninstalled the app, cleaned the project and the problem still occurred then the problem is somewhere else.
Are you sure that the files are listed in the files tab?
Click on Sync button in the files tab.
Make sure that the actual files are lowercased.
Hello Erel
After a bit of digging around I have found the problem / solution.
The app created a list of files from the asset folder
it then used the files with .png as a extension
I was unaware that the assets folder contained other files and the app was trying to use them.
So i renamed the files i need to use and parsed them that way.
Every day is a school day.