Using HelloTitledPane with VoiceOver can't move focus into the contents of a TitledPane using Control + Option + arrow (or via Control + Option + Shift + arrow if that might even make sense). With normal tab navigation this can be done.

The workaround is to use tab navigation rather than VO navigation.

This is a P4 and can be deferred. It warrants a note in the VPAT and release notes.