Hello (I am still using version 2.2.10),
I finished and formatted (changed the vertical staff spacing in the parts from 10 to 6 spaces) a piece in Eb Major. Saved everything.
Then duplicated the file in the finder, opened the copy and transposed the piece down to D Major.
Strange thing: the vertical staff spacing in the parts is back to 10 spaces. Why is this?
If any of the system formatting of the parts changed, e.g. because more or less music could fit on any given system, then any manual overrides to staff spacing will have been removed. Staff spacing adjustments are tied to the rhythmic position at the start of a system: if that changes, the adjustment will be removed.
Thank you for the explanation David.
The transposition changed some parameters in a way () that the original formatting could not be kept.
() i. e. two sharps instead of three b, the slightly different position of the notes, different accidentals, possible different stem directions…
You’re welcome… though my name’s not David.
oh, sorry Dav… I mean Daniel 
… my two nephews are called David and Daniel, and I always mix their names up …