Hello @Okard,
as far as I could see, your code is correct. There is a know bug reported 02/2021: https://community.kobotoolbox.org/t/dynamic-choice-label-with-choice-filter-update-problem-in-enketo-kobo/15986.
Maybe @Kal_Lam can tell more about the status of the issue (e.g. GitHub?).
