Hi @JS,
Did this problem appear with all .pptx files in OneDrive?
Could you provide the error message?
Try to download the file to local and check if you can open the file without problem.
Go to https://onedrive.live.com and check if you can find the file in web.
Try to provide more information about your problem, so that I can get more accurate solutions to this problem. I’m glad to help and follow up your reply.
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