Prior to SU6 any custom ILS nav approaches I added to a user created airport (that has no nav approaches in the sim) worked and were selectable in aircraft avionics. Similarly I was able to select such an approach from the world map planning screen.
Since SU6 any attempt to load such an approach on the world map planning screen or in an aircraft's avionics system causes an immediate crash to desktop.
I can supply a sample project folder download link (by Private Message) with source code and compiled build to help with diagnosis if that helps.
I notified Zendesk of the ctd issue and they referred me to this forum.