Not quite the Ozarks but this thread caught my eye - we've had very similar reports here in Nottinghamshire for years. Big black cats, way larger than any domestic, spotted around the forest edges and farmland. Locals call them the "Beast of Sherwood". Though the press rarely takes it seriously.
A few things I'd be curious about with your sightings:
Size comparison - when you saw it, could you gauge it against nearby trees, fencing, anything fixed? That detail tends to be the most convincing when people are sceptical, Movement - did it move like a domestic cat scaled up, or was there something different about the gait? Witnesses here often describe an unusually fluid, low-to-the-ground movement, Any vocalisation? There've been a couple of reports here of a deep rasping call at night that doesn't match anything native
Three sightings in a single month from the same area is genuinely significant. That kind of clustering usually means either a resident animal with a established territory, or possibly more than one individual.
Has anyone managed trail cam footage yet? That's where I'd be putting my energy if I were local to you. The Ozarks terrain looks dense from what I've seen - presumably plenty of deer which would support a large predator.
Would be really interested to hear whether any livestock losses have been reported nearby. That tends to be the detail that finally forces an official response, however reluctant.