Hi,
In SharePoint Online we cannot preview .TXT files if the user has the "Restricted View" permission set in the folder that contains the file.
But other file extensions like .PNG, .MP4 .DOCX are previewed just fine !
For .TXT files the message is:
Hmm... looks like this file doesn't have a preview we can show you.
"Restricted View" means the user can view pages, list items, and documents. Documents can be viewed in the browser but not downloaded.
I know the workaround but I would like this bug to be fixed.
The workaround is to set the user permission a little bit less restrictive to "Read", that means the user can view pages and list items and download documents.
