When you try to recode a column that has the List Check property, and the recoded value you want to use is not in the list of items for the list check, Recode gives you a warning that this has happened, but then it appears that it will allow you to do the recode. However, when you click ok the recoding does not actually happen.
I think it would be good to have the option in Recode to either delete the List Check property or update the list check property with the new value that has been added with recode.
The use case is when you have a column with a list check that has missing values, and you want to recode the missing values to another value (e.g. "Missing") so that you can use that as an informative missing category for prediction purposes.