Keyboard shortcuts for 16th/32nd sub-beaming doesn't work

This was way back three years ago, verified by Marc S, but apparently forgot to file an issue: https://musescore.org/en/node/110381

16/32 sub-beams don't work when attempted to be triggered via keyboard shortcut.
Apparently no one caught this or updated it, so getting it on the issue-tracker now.
Should be a fairly simple-fix... but never looked into the code about it.