custom keyboard shortcuts

Summary:

While trying to customize the keybord shortcuts with the modifier "CMD" to "CTRL" I seem not to be able to change "ungroup" from SHIFT+CMD+G to SHIFT+CTRL+G

Steps to reproduce:

• open Inkscape
• open preferences- keyboard- selection
• double click to change short cut
• change "ungroup" from SHIFT+CMD+G to SHIFT+CTRL+G
• change "objects to guides" from SHIFT+G to CMD+G
• close preferences

What happened?

Inkscape 1.0

• using the new "ungroup" shortcut still results in "objects to guides" to "ungroup" the selection I still have to use the default shortcut SHIFT+CMD+G

Inkscape 1.1

• crashes after closing preferences
• Reopening Inkscape and the preferences some of the shortcuts have disappeared, trying to replace them again Inkscape tells they already exist.
• Using the new "ungroup" shortcut still results in "objects to guides" to "ungroup" the selection I still have to use the default shortcut SHIFT+CMD+G

What should have happened?

Using the shoutcut SHIFT+CTRL+G = "ungroup" selection

Sample attachments:

Version Info:

- Inkscape Version: Inkscape 1.0 and 1.1
- Operating System: mac 
- Operating System version: OS X 10.11.6