Selecting table columns and rows isn't working

I have a table that is actually formatted as an Excel Table.

Normally, I can select columns and rows using this:
https://support.office.com/en-us/art...6-79e4008af1d3

But it stopped working today. Now I can only select the entire row or column...not just the data in the table.

Any ideas why this might be happening? And even more importantly, how do I fix it?

Attach a sample workbook. Make sure there is just enough data to demonstrate your need. Remember to desensitize the data.

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