This issue is only within the image display of the block mask. The block will work as intended and produce no errors when simulating or deploying models to hardware.
In order to fix the image display you can do the following:
In the MATLAB command window, execute:
Navigate to the following path >> SupportpackageRoot\toolbox\target\supportpackages\vexarmcortex\blocks
Replace the file "vexarmcortexlib.slx" in that directory with the one attached to this post.