Hi LibbyEAP,

1. Are you using Windows built-in zip file feature or any non Microsoft program to unzip files?

Try the following steps and check the result.
Step 1: Unblock the zip file
a. Right click on the downloaded zip file and click Properties.
b. Click Unblock button present under the General tab.
c. Click ok to apply the changes.
d. Unzip the file and check the result.

Step 2: If the issue persists, zip the file and unblock the folders
a. Press Ctrl+A to select all the folders. Right click on any folder and click Properties.
b. Click Unblock button present under the General tab.
c. Click ok to apply the changes.

Step 3: Unblock all the office files
a. After unzipping the files, select all the files, right click on any file and click Properties.
b. Click Unblock button.
c. Click ok to apply the changes and check the result.

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Hi Syed,

Thanks for your answer.

I'm using the built in Windows feature to [Extract all files].  I've tried the steps you suggest with the following results:

Step 1 - I can unblock the zip file, but this does not unblock the individual files once I've extracted them. 

Step 2 - The individual folders do not have an Unblock button - just the files within them, so Step 2 does not apply to my files.

Step 3 - If I select any individual file, I can open its Properties and Unblock it; however, if I select all the files in a folder, the Unblock button does not show - so I cannot unblock them all at once in this way.

I would be very grateful if you have any further suggestions to help me.

Use powershell Unblock-File...

Start Powershell

cd to the directory where the unzipped files are...

PS C:\Downloads> get-childitem -file -recurse |  unblock-file

If you want to see what files this will action, then add the -whatif modifier.

PS C:\Downloads> get-childitem -file -recurse |  unblock-file -whatif