Greetings Cotton,
Am I understanding that you are using a common "two into one splitter" to combine antennas on the mast?
This looks like Antenna A coax to splitter on mast, Antenna B coax to splitter on mast, coaxes combined to single lead down into home.
Your reception plot is very nice. If I had set this up, I'd have had both antennas as you have set them up. Antenna A runs dedicated lead into selectable A/B switch in house. Antenna B runs dedicated lead into house on A/B switch. This configuration creates antennas that are dedicated for Tri-Cities or Knoxville. From A/B switch feed 8 port Channel Master distribution amp. Each TV gets dedicated lead, no splitting a individual lead six times.
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If I read your post right, both antennas are feeding into the same line. This can cause odd conflicts and cancelling out. If combing antennas normally one antenna handles VHF and the other UHF. This requires a VHF/UHF combiner.
The other way is what I outlined above a A/B switch on the system to keep antennas separate from each other.
A test right now, without spending any money is to take single lead from antenna, feed into ONE TV and watch. If signals are stable and acceptable, this is a distribution problem. If signals aren't satisfactory, this may be an antenna or antenna location issue.
Are you shooting through trees?
Cheers.