Why do I keep getting the error message "value must match one of the listed items" in an excel multi-select list?

Question

I have inserted a VBA code from https://www.ablebits.com/office-addins-blog/create-multi-select-dropdown-excel/#comment-714534 to enable me to select multiple items in a dropdown list.

It works perfectly for me if the cells aren't formatted as a table. When I change the formatting to a table and select more than one item I get an error which says "The value in this cell is invalid or missing. Click on 'Display Type Information' for more details".

When I click on 'Display Type Information' it comes up with the following:

"Data Type: List Restriction: Value must match one of the listed items.

Blanks will be ignored and are automatically valid."

I get this error even if the only options in my dropdown list are Yes and No. I tried this as I thought it might be a problem with the length of the options I had originally.

I've also tried opening a new excel sheet and I still get the same problem.

Is there a way to fix this?