SOLVED! 

Apparently I missed it the first 20 times I read the safe harbor...

From the second to the last paragraph on page 4 of Rev. Proc. 2019-38

"An interest in mixed-use property may be treated as a single rental real estate enterprise or may be bifurcated into separate residential and commercial interests.  For purposes of this revenue procedure, mixed-use property is defined as a single building that combines residential and commercial units.  An interest in mixed-use property, if treated as a single rental real estate enterprise, may not be treated as part of the same enterprise as other residential, commercial, or mixed-use property."