Logic Pro X 10.3.1 - Tracks randomly muting, notes completely muted

Hey,

I am running Logic Pro X 10.3.1 on a MacBook Pro (TouchBar and Touch ID, macOS High Sierra (10.13.3), 13" Model, 2016, 2.9 GHz Processor), and I am having quite a big problem.

There are tracks that are randomly muting, and there are keys that seem to be permanently muted. I have tried deleting the user preferences, and I have checked the custom key commands, and nothing looks fishy, yet the tracks are muting at the most annoying times. The most annoying is when I am bringing up the Musical Typing Keyboard. The entire track seems to be muted, and I have to constantly be pressing 'M' to unmute it.

Also, when I am using the Musical Typing Keyboard, some notes are COMPLETELY muted. I've tried everything that I can find online to sort it out, but nothing is working. The specific keys that are muted are D1, C2, and D2. I would be 'typing' a melody for a track, and then some of the keys would be muted. I would then have to go into the Piano Roll to fix it, and manually fill in all the gaps. (And depending on the key it's in, and the style of the music, it takes a VERY long time.)

Any help would be appreciated, because it's very annoying!

Thanks very much.