Text messages delete themselves

Settings > Messages > Keep Messages [Chose your option]

Watch the GIF below

I delete one text message and the message directly below it was randomly deleted too. I noticed it occurred within days of an OIS update! I called apple support. They had me shut my computer down, bring it back up while holding the Shift key which put the computer in Safe mode. In this mode I saw the missing texts. This mode automatically detects and fixes operating errors. Then I shut down and restarted. Problem fixed! My Mac Pro is 2014 mid-years with the most current operating system update. Apple support remains a great option and resource.