I still have TV reception issues. Why would the TV in the basement and the one on the second floor receive different channels?

The 1986 roof antenna (Old Faithful) is working just fine; the TVs are high-end flat screen 46” ones purchased within the last 5 years; one doesn’t get Fox…the other does but drops one of the networks. No cable issues because I don’t have cable (or satellite). Hardly a serious problem but a curious one. The TV man shakes his head and talks about the position of the large leafy trees on my property, a bogus issue because the leaves fall off in winter.