The latest Goodnotes doesn’t let you type in a hex code to change the TEXT color on a SHAPE. This happens on the Custom tab of the Color Change pop-up window when you select the text on a shape and then click the color dot on the pop-up menu to change the TEXT color. Goodnotes doesn’t let you insert your cursor into the Hex Code box. There are just a bunch of zeroes in the Hex Code box that you can’t overwrite.
The shapes themselves can be updated using a typed-in hex code, but not their built-in text. This problem happens regardless of which auto-shape you are using, including the triangle, circle, diamond, square, and auto-detect shapes.