Custom shortcut for insert Silence no longer works in Audition

Having a bit of an issue with Audition 13.0.13.46 on Mac

I had assigned the keyboard shortcut of 2 to insert silence, this as worked flawlessly for months.

Then for some reason it stopped working.

Here's what I've tried to do to fix it:

Assigned other shortcuts to the key "2" - these work fine.

Tried to assign different keys to apply silence - nope nothing.

Tried other keyboards - nope nothing.

Tried changing the language of the keyboard - nope that doesn't work either.

I've even tried to delete the custom XML file that doesn't work either.

I've done no updates and I've restarted my machine and Audition countless times.

Does any one have any advice on what the issue could be?