Shortcuts created or edited to use the number pad don't get saved as Num+

Issue type

UI bug

Bug description

In version 3, I used the number pad "+" to create ties. Version 4 changed the default to "t", so I tried to create a shortcut.
In the shortcut editor, double-click Tie, then press the "+" key on the number pad.

Two errors:

1. The shortcut editor shows only "+", not "Num++" (it does SHOW Num+X for a few default shortcuts)
2. After closing the shortcut editor, pressing the "+" above the equals sign then creates a tie, but pressing the "+" on the number pad does NOTHING

Steps to reproduce

1. In the shortcut editor, double-click Tie, then press the "+" key on the number pad.

2. The shortcut editor shows only "+", not "Num++"

3. After closing the shortcut editor, pressing the "+" above the equals sign then creates a tie, but pressing the "+" on the number pad does NOTHING

Screenshots/Screen recordings

No response

MuseScore Version

OS: Windows 10 Version 2009, Arch.: x86_64, MuseScore version (64-bit): 4.0.2-230651553, revision: github-musescore-musescore-dbe7c6d

Regression

I don't know

Operating system

Windows 10

Additional context

No response