I would check the code.I definetely think its a wind related incident. We have 1/2 acre lots with NOTHING between them.....and they are almost all backyard. Spring's a comin, so we will find out sooner than later if it is resolved.
@Gunbuffer, i believe it vents to the attic, but i'll have to double check. I did double check if it was drawing anything when running and it definetley does.
Venting an exhaust fan into the attic may be against code. That’s worth checking and something tangible you can go after them with.