Just as an aside, I had the same symptoms of missing next waypoint on the HSI source when I flew yesterday.
At one point I selected the A/P menu, instead of using the A/P controller or touching the HSI source box on the screen. I deselected NAV and then cycled through the two HSI sources I have until I got back to SkyView. I then re-engaged NAV and had the next waypoint appeared on the screen.......so it's still there somewhere. This lasted until I arrived at the first destination.
Later, on a second flight, I tried doing the same thing when the next waypoint was missing but had no luck at all.
In particular, the next waypoint didn't appear if it wasn't a known waypoint i.e. just a position on the map. I've never noticed before if this was normally the case but I THINK it displays it as waypoint 5 or similar. If this is the case, then no waypoint 5 appeared on the flight plan list.
I appreciate some of this is a bit waffly but, in truth, I don't think I've ever noticed the next waypoint on the HSI source and I've probably looked at the flight plan a couple of times ever. I fly the same route a lot and my aircraft could probably find its own way without me even being in it
