Welp... there you have it. Fast Track Pro has been reported to cause this type of issue. I'd see if there are any driver updates from M-Audio and see if the forum or tech support can help get your settings where they need to be.
Seriously some people have no problems with the Fast Track and others report problems. No idea why. I came very close to buying one myself but settled on the Focusrite 18i6. Couldn't be happier. Cheers.