From my memory the usual behaviour used to be:
- Sections that contained only fields that were set to not be visible would also not be visible (i.e. hidden as there was no content to display)
- Tabs that contained no visible Sections would also not be visible (i.e. hidden as there was no content to display)
- In the UCI Tabs containing all items not visible are being displayed (showing no content but still a Tab for the user to select and see an empty page)
- When back in the Classic Interface (remembering that it is not yet discontinued)
- Tabs that contain Sections (set to be visible by default) where the Fields have been set in the Form Editor to not be visible by default are displaying the Section Heading and a thin empty content area
- Tabs that contain Sections (set to be visible by default) where the Fields have been set in the Form Editor to be visible by default but are set not visible via a Business Rule are not displaying the Section (no heading or content area.
For point 2. the outcome should be the same, but for some reason they are now different.
For point 1. Given that Business Rules don't let you hide Sections or Tabs, the Tab should be Hidden.