Instrument name gets wrong position and a line is missing during note entry when "Hide empty stave" is enabled
Steps to reproduce:
1) Create a new score with some instruments. (eg Bb-Cornet and Bb-trumpet).
2) Add some note in the first and second bar of the upper instrument (Bb-Cornet)
3) Create a line break in bar 1 such that the first line contains bar 1 only
4) Switch on Style->General->Hide empty stave
5) Start entering quarter notes in bar 1 of the lower instrument (Bb-trumpet) and observe what happens
1) After 4 quarter notes are added, the blue cursor jump down to the empty part of the "page". (probably ok?)
2) When 1 quarter note is entered in bar 2, the next line shows. However, the instrument name is positioned far too left and the line "connecting the two instruments" is missing:
3) When a second quarter note is entered the layout looks correct:
This is essentially the same issue as #25168: Instrument labels incorrectly placed after hide empty staves is unchecked, but I'm leaving this open as it may turn out two separate fixes are needed.