File becomes corrupt as soon as music is entered
Open the attached MuseScore file. It has just been created from the "create new score wizard." All I have done is change the staff names for clarity. However the file becomes corrupt as soon as you enter a note of music!
Click on the first bar of the uppermost staff (Gtr. 1). Go into note entry mode and enter a D quarter note (4th staff line). As soon you do so the measure rest in Gtr. 2 disappears! If you now save the file and try to open it, you will find it has corrupted.
If you start again with the fresh uncorrupted file, try entering a standard staff bracket to link the treble and TAB staff of Gtr 1 (double-click on the staff and extend it downwards). Then, in the same way, create another bracket to link Gtr. 2 staffs. The Gtr. 1 bracket will return to its default length! You can try saving this file and reopening it to test if it has also corrupted.