Announcing a more intuitive sharing experience across Microsoft 365 for better collaboration

I'm grasping at straws now so I apologize if this isn't the right place for this. But I have a user who relies heavily on the Preview Pane in File Explorer for previewing files. I never use this feature so don't know its normal behaviour. My user insists that up until a couple of days ago, she was able to preview all types of files for any file stored in OneDrive in the cloud. However now, she can only see previews for some image file types, but no document types. On my own computer I can see previews for .png, .jpg, ,ico, .svg and others, but I cannot see previews for .pdf, .docx, .xlsx, .ini, .txt or any other similar file types. I have tried numerous preview pane repair options, MS Office repair options, uninstalled and reinstalled OneDrive and so far nothing is fixing things.

During one set of internet searches I was finding some information that seemed to imply that NO cloud based files would provide a preview until downloaded to the computer. Being able to see SOME previews for some file types would indicate that implication is wrong. Today, while doing further searches, I've found information that seems to indicate that I should be able to see previews for over 300 file types! Yet this information is not clear on whether or not these files can exist only in the cloud and still provide a preview, or if they must be downloaded first.

My user is confident she was able to preview all file types without needing to download them first. And with her being an Executive level individual, I really don't want to have to tell her that the thing she could do fine last week is no longer possible.

So please, can anyone point me in the direction of some useful information on fixing this or that will clearly and definitively indicate what is and isn't possible?

Thank you.