Autocorrect "Text Only" box greyed out in calc

I’m trying to make an autocorrect filter where if I type a small code ( [x] ), it changes to a longer bolded word ( X is good ). From what I understand, I should be able to do this by selecting an example of the bolded output text, opening the Autocorrect Options, unchecking the “Text Only” box, and entering the text to be replaced. However, the “Text Only” box seems to be greyed out no matter what I do.

I tried also to work around this by replacing to text with asterisks around it, but this did not work. It just placed the asterisks as plain text. Any solution/workaround?

Text only can only be accessed if you have selected text in your document. When ticked, it will ignore any formatting. Not ticked, it will replace including the formatting.