I made device panels for my MS2000, Nord Lead2 and TritonLe.
I have the same issue, I have lost some amazing sounds due to this little bug.
My work around is saving the patch before I close Nuendo. If I remember that is…
Next time I load the song the panels are all set to default, but at least my sound is there.
Not sure if that will work in your case.
Seems like this feature/functionality has been left at the door some time ago.
Haven’t seen or heard of any updates to device panels in many years.
I can’t even edit panels in any version past Nuendo 5.
As soon as I try to open a panel for editing, I get cascading error windows in all versions after 5.