Not my area geographically but big black cats are reported all over the place and the pattern is always the same - multiple sightings in a short window then nothing for months. Three times in one month is worth documenting properly. Get exact locations, times, any photos even blurry ones.
The "black panther" thing in the UK is massive, we get them constantly in rural Scotland. Officially they dont exist here either but the sighting reports go back decades. Most serious researchers think theres a breeding population of escaped or released melanistic leopards. Could be something similar going on in the Ozarks, that terrain would hide a large cat pretty easily.
What size are we talking, rough comparison to a dog or bigger?