Hi @David C,
Thank you for posting your question in the Microsoft Q&A forum.
According to your concern, I suggest you checking this guideline to see if it helps resolve the issue. You can skip any steps that you've tried but had no positive results:
1- Remove the Mark of the Web (MOTW)
- Open File Explorer, navigate to your Excel file that having error
- Right click on it and choose Properties
- In General tab, check the Unblock box for the Security option.
- If the Unblock options is not available, it's usually because that your file is currently saved in a OneDrive or SharePoint folder and it will be considered as from the internet.
- You can try disconnecting OneDrive/SharePoint temporarily or move the file to your local folder and try the Unblock Security box again.
2- Double check the Trust Locations settings
- Open Excel and go to File > Options > Trust Center > Trust Center Settings
- Select Trusted Locations in the left bane > check in the list if your file path has been added in there.
- If not, press Add new location > Browse and navigate to the folder where you keep the files
- Press OK to close all the dialog boxes then try opening your excel file again
3- Enable macros in Excel
- Go to File > Options > Trust Center > Trust Center Settings
- Click Macro Settings and choose "Enable VBA macros" (since you're sure the file is safe)
- Then click OK to save the settings
4- Disable Protected view
- Go to File > options > Trust center > Trust center settings
- Choose Protected view and uncheck all the options
Please understand that our initial response does not always resolve the issue immediately. However, you can try these steps and let me know if it works for you. If not, we can work together to resolve this.
Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments so I can continue to support you.
I look forward to your response.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.