Custom fields in tabs not displayed in View Screen

We have a View Issue screen with multiple custom fields on both the default tab and a second tab.

Even when there are values in the custom fields, some from the second tab are not display on the view issue screen at all. The ones that are displayed are all shown on one page. No tabs are displayed.

We are observing this on a test instance prior to upgrading our production instance running 4.3. In that version the fields are all displayed, but again all on one page. Can't help wondering what the point of tabs is if they are ignored, but that's another story.

In my search prior to raising this I saw JRA-33758 and thought this was the same, but what we are seeing is slightly different in that some fields are displayed, but not all of those that have a value.