Microsoft confirmed that the addcustomview() function is not supported in offline mode. Before release wave 2 2021, we used the function to create a custom View that would only show the Labour Codes assigned to a Bookable Resource via the Bookable Resource Category.
This view was then used when creating new Time Entries on a mobile device in Offline mode (using Field Service Mobile app) - when a Bookable Resource was creating a new Time Entry and they needed to select a different Labour Code to their Default Labour Code, they would only be shown the Labour Codes associated via the Resource Category Association.
As the addcustomview() function is no longer supported in Offline mode, it requires a User to search for a Labour Code via the Advanced Lookup; i.e. when a Labour Code is required that doesn't equal their Bookable Resource's Default Labour Code. This opens up the ability for the mobile User to select a Labour Code that is not associated with the Bookable Resource's Resource Category and thereby affecting Field Service's data integrity.
The suggestion is for the addcustomview() function to be fully supported in Offline mode.