Bink63 First, I think the problem is solved with the slight shift in antenna position. Second, the difference between the TV with interference and the one that doesn't is that the newer one receives the new/different ATSC 3.0 transmission and part of the improvement in the new technology is specifically to combat multipath interference. So, rather than ruling out multipath as the problem it makes it the prime suspect.
As for flight patterns you are correct that 'most' goes far south, but I know what I see and hear, and there are planes nearby. Here is a site with a live view and as I'm posting I see 6 in the Arlington Heights - Wheeling area pretty close to me.
https://webtrak.emsbk.com/cda
They might be from Chicago Executive (used to be Palwaukee) though. But I think O'hare traffic is pushing north too. Sometimes I hear the rumbling sound of larger planes south of me, while the smaller executive jets screech to the north.
https://www.therecordnorthshore.org/2024/12/23/look-out-above-change-in-flight-patterns-has-planes-flying-over-wilmette-like-never-before/