I haven’t yet successfully used editable text boxes online.
It might be worth changing your Text and Padding to Constant rather than Set Every Repeat.
However, the error you are getting is similar to a manual translation I have to do when making editable text boxes in code.
Python .upper() translates to JavaScript .toUpperCase()
According to Error with textbox: TypeError: state.toLowerCase is not a function - #8 by kellycotton it should work in 2020.2.10 so perhaps you are still running an earlier version.