When you select a note (or notes) and click on 'Small' in the Note section of the Inspector the note(s) vanish. They disappear altogether, not even visible when 'Show invisible' is selected [using iMac with OS X El Capitan]
Closed due to lack of information and inability to reproduce. Please report, with precise steps to reproduce, in a new thread (or reopen this issue) if this still troubles you in the latest version (3.4.2).
Comments
Can you attach the score you are having problems with
Check the settings in https://musescore.org/en/handbook/layout-and-formatting#style-edit-gene…
Maybe you've set those to something insanely small? Default is 70%
Closed due to lack of information and inability to reproduce. Please report, with precise steps to reproduce, in a new thread (or reopen this issue) if this still troubles you in the latest version (3.4.2).