text.sourceText.style expressions not working

Using After Effects 25.1. Linking the FontSize to a Slider using the expression:

"text.sourceText.style.setFontSize(effect("Slider Control")("Slider"))"

But I'm getting an expression error reading:

"Error: property or method name 'style' in Class 'TextProperty' is missing or does not exist. It may have been renamed, moved, deleted, or the name may have been mistyped"

All of the expressions are still auto suggesting with the Expression Language dropdown menu. As I start typing "style" after "sourceText" it starts to autofill. Why is "style" gone all of a sudden? How is After Effects not being able to reference it even though it's showing up in the dropdown menu?