I know it's been a while since this post has been active, but I just found the forum so I'll add my experience here. I have a 2019 Mazda CX-5 Signature Edition. Absolutely love it except for this noise issue coming from the roof rails. At about 90 mph airspeed (not speedometer speed) I get this noise coming from the roof rails. It's a single tone noise, it's loud and annoying. If I'm driving in non-windy conditions or with a tailwind then it's not much of an issue. But if I'm driving 80 mph into a 10 mph headwind (or 70 mph into a 20 mph headwind) then it's really a bad cabin experience. I keep forgetting to look for fixes like this and the pandemic has made road trips less frequent, but I'm about to go on a 12 hour road trip and I finally remembered to check for a fix. I will try the tape over the "cap/rail" junction and report back. My Mazda dealer admitted that it was a known issue but I'm disappointed that they haven't stepped up with what seems to be an easy fix for this. I can deal with some electrical tape for long trips. Zoom Zoom ya'll.