Hi @Anonymous,
I see that you are visiting as a new member to the AutoCAD Mechanical forum. Welcome to the Autodesk Community!
I am also not seeing the issue you described. A couple things I can think of that may be causing the issue are the updates for AutoCAD Mechanical and core AutoCAD are not installed (both need to be installed for some features to function properly), or the user profile is damaged.
To install the updates, see Update software in Autodesk Account | Download & Install
For a damaged user profile, see How to reset AutoCAD to defaults.
As a workaround, other methods are available to edit the aliases, my preference is through the PGP file. This can be done from the Manage tab in the ribbon. In the Customization panel select Edit Aliases, then Edit Aliases from the drop down.

This will open the PGP file that stores all command aliases. There is a section a the bottom of the file called User Defined Command Aliases that is designed to override any of the native command aliases. In AutoCAD Mechanical, this section includes all the AM specific keyboard shortcuts.
I like using this method since it is in a basic text format, can be saved out and edited in a text editor, then copied back into the file. Just follow the format as used with native commands. Here's what a portion of mine looks like:

See To Edit the Program Parameters for more options.
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All the best,
Cheryl Buck
Technical Support Specialist

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