on my MAC, PPT doesn't show any preview if i am not open the individual of each.

Thanks for the additional details, AnnHC9.

We'd like to narrow things down a bit so we can better understand what might be causing the behavior. The most obvious possibilities are that either something with Powerpoint is causing the issue, or some setting in your macOS user settings.

So, let's try creating a new user account on your MacBook Pro, and seeing if the behavior happens there. If it does, that will help us rule out your user settings and we can focus on solutions with the app developer: How to contact an app developer.

If the issue goes away in the new user account, it indicates an issue with your account's settings and preferences, and you can Contact Apple for support and service.

Give that a try, and see how it goes.

Keep us posted.

Thanks for reaching out, AnnHC9.

It looks like some of your files aren't showing a preview inside the folder. We can help.

From your screenshot, we see that some files are still showing a preview correctly. Is there any change if you open any of the files and then view them in the folder again?

Let's also go ahead and update the macOS by following these steps: Update macOS on Mac.

Let us know if the issue continues after updating the macOS software.

Take care.

Thanks for following up, AnnHC9.

From here, you'll want to use the links we provided earlier to either contact the developer of Powerpoint, which is Microsoft, or contact Apple Support. The steps we provided will narrow things down so you'll know which group is more appropriate to reach out to for help.

Take care!

I am having the same issue and it's incredibly frustrating!!! I have hundreds of PP presentations and have no idea what-is-what by the names only -- I need to see the preview thumbnail -- It's only the PP, not the jpegs ---please tell me you have worked out why this is happening.... It's driving me crazy and making some areas of my job absolutely impossible.