Keyboard shortcuts revert to defaults instantly

Steps to Reproduce Bug:
Open preferences, change keyboard shortcuts, close preferences

Expected Behavior:
Custom keyboard shortcuts are maintained

Actual Behavior:
All keyboard shortcuts reset to default as soon as preferences window is closed

Version Number:
MuseScore version (64-bit): 3.0.0, revision: 10ebbb9

Operating System:
macOS 10.14 Beta (18A347e)

Additional Details (and how I tried to resolve it):
Normally I use Sibelius for music notation, but I find MuseScore better in some ways (it's free, so it's better for distributing scores to friends/coworkers; it also handles lyrics for choral works better than Sibelius and just runs more smoothly). Since I'm very accustomed to the Sibelius keyboard shortcuts, I changed MuseScore's shortcuts to match. This works fine in the most recent stable release of MuseScore 2, but I cannot get it to work in the 3.0-dev builds. Every time I change the shortcuts, they immediately reset to default once I close the settings window.

Additionally, using the "Save" function for the shortcuts in 3.0-dev simply saves a .xml file with the default shortcuts, not the custom entries. I even tried replacing the "shortcuts.xml" file under "/Users/USER/Library/Application Support/MuseScore/MuseScore Development" with the custom "shortcuts.xml" found in the MuseScore 2 folder. Even after swapping the file, MuseScoreNightly still only uses the default shortcuts. Changing keyboard shortcuts is a pretty standard feature of any music notation editor, so without it working I feel that it renders the software very cumbersome and downright unbearable to use.

Attached File:
I've attached the custom "shortcuts.xml" file that I use in MuseScore 2