Hello,
can you share an image of the forms or fields used to update those records in those collections? there could be multiple factors leading to those records not being updated, if you can share screens of your app, or how your collections are linked I can take a look and help you. Sometimes some fields have to be set to automatic, so they have linked automatically, few things to review.
Share some screens on what you want to accomplish and how they are set and I ll try to help you as much as I can.
Thanks