Spreadsheet functions within Apple pages not working.

All of the sudden, without warning, I try to insert a table and/or copy-paste a spreadsheet from Numbers into my Pages document and I can’t add formulas to it. I insert the = sign and the fx menu used to pop up, but not any more! I’ve tried creating a new document as well as editing old documents with tables. In all cases, the fx function is gone. I can only insert text or numbers…no formulas. Why?