S7 repeatedly shows new messages

[gregsharpe]

As of October 2018, my S7 (version 8.0.0) has been showing unread messages. When I open the native messaging app, there are numerous messages from varied contacts that are shown as new. I open the messages and a few minutes later they return being shown as new. I've read through the other similar problems, but all the solutions are many years old and do not seem to apply to my OS. Someone else must have had this problem?