Hi @Barry Schwarz ,
What's the version of your Outlook desktop client(File>Office account>About Outlook), please first ensure that you have updated to the latest version of Outlook client.
Did you change the view settings in the default view(such as compact,single and preview) or in a new customized view?
Based on my research, I found a similar thread that mentioned it may be reset if you change in default view directly, and the issue may also caused when your customized view setting is corrupted, in this case, please try to create a new view like below (Change view>Manage views)and customized the conditional formatting there to check, it's also recommended to make a copy of the new view so that we could restore your view when we need.
Hope that would be helpful to you.
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