reading text files and displaying them in OneDrive fails to solid white screen

Using iPhone 14 Pro, iOS 16.4.1, OneDrive app (Microsoft Office cloud used on Dell PC syncs), I am able to open the app and view folders and documents. EXCEPT all of a sudden, any text file I saved displays an all white screen. The text has disappeared. At around the same time, I noticed that when text documents I see online switched from white background-black text to black background-white text. I must have toggled a switch somewhere, in layman's terms?

Does anyone have any idea how I can switch back? (If that is the problem)