How to convert text values like $1,234.56 into numbers?
This happens because there is a leading apostrophe in the cell which means "treat this as a literal value and don't interpret it." If you remove the apostrophe, Libreoffice will treat it as a number/currency.
Based on https://ask.libreoffice.org/t/how-do-i-get-rid-of-the-apostrophe-before-a-number-in-calc/52632/2