Update:
I dropped my car off before work hoping the dealership would discover and repair the rattle. Instead, they gave it a loaner car and told me to return it later that day. Sweet! The tech was able to conduct some road test and was able to diagnose the issue. It turned out the clear plastic portion of the instrument panel was loose or something and would rattle under certain road conditions and braking. The fix required disassembling the dash and applied "felt tape to all contact points between the lens and cluster." The noise is gone and all is quiet again.
Kind of off topic:
I received a 2018 3 auto GT hatch in Snowflake as my loaner vehicle. Compared to the CX-5 sport, I noticed some differences in driving dynamics. The hatch felt more planted to the group and would hug turns faster and tighter than the crossover. The steering was sharper and more precise. Acceleration between the two wasn't night and day but I did notice the difference. The hatch would cruise at 5th gear no problem when speeding up while the crossover felt sluggish and would downshift. The other amenities of sunroof, Bose, HUD, heated leather seats, auto climate control and XM radio were nice to have. It makes me wish I had splurged for the GT version of the CX-5 but I don't really need it. Having no car payments is satisfying enough for me.