Not my usual territory (I'm more of a spontaneous combustion nerd from Wales) but big cat sightings genuinely fascinate me as a side interest. We get loads of similar reports in the UK - the Beast of Bodmin, various "phantom" big cats spotted across Wales and Scotland. Authorities always dismiss them but the sheer volume of credible witnesses makes that position harder and harder to defend.
Three times in one month is significant. That's not a trick of the light or a misidentified dog, that's a pattern. What kind of terrain are you spotting it in - woodland edges, open ground? And rough size compared to something familiar?
The escaped exotic pet theory gets thrown around a lot for UK sightings and I imagine its the same over there. Melanistic leopards or jaguars do exist and people kept all sorts before the laws tightened up. Would love to hear more detail on what you're actually seeing because the consistancy of these Ozarks reports from different people over the years is really something.