Calendar doen's update

at first sorry about my english, i hope everyone understands my question.
i use nextcloud 14 and the calendar app. i included the calendar with the abo-link to my google-calendar; that works! when i make a new entry or when i delete an entry my google calendar also updates after some hours; so that works also and google updates it!
BUT when i move an entry or i change something i canโ€™t see this change in my google calendar!
so i think that the error is not at google because they update, but they donโ€™t get all infos when something changes.
please help!!

thx, franz