To update this thread, looks like it is an issue with the 2018 Mac Mini and potentially newer Mac's with USB-C. There is a driver reset that occurs, this causes a drop out. There are a number of RME users who have run into this (those using RME in studios, not recording vinyl). RME has logged the issue with Apple, but there is no real feedback on when it will be addressed. I tested the RME on an older Mac laptop with USB type A connectors and a PC with USB type A connectors, no issues at all. A work around is using a Thunderbolt 3 hub as it bypasses the issue. Sucks because the least expensive option was $100.
Been a loyal Apple user for nearly 20 years now, but they've really been shitting the bed as of late.... the new Mac Mini has been really frustrating to use. My old 2010 Mini was great, only upgraded because it was running very slow, at this point I'm thinking of switching back to my old Mini!