After Office 2019 C2R updated itself from version 16.0.12827.20470 to the latest version, Outlook 2019 crashes on several Windows 10 Pro PC's when I select Rules -> Manage Rules and Warnings.
Are there any error prompts in Outlook when this issue happens?
What is the specific version of "the latest version" you mentioned here?
According to your description, it seems that your issue is more related to your Office update. So, to do tests about your issue, I installed Office 2019 C2R on a completly new computer and update Outlook to Version 2007 Build 13029.20460. Then I added IMAP accounts to Outlook and selected "Rules -> Manage Rules and Warnings" and found that Outlook can work fine without any issues. So, it seems that I could not reproduce your issue.
If your Outlook version is older than mine, please try to update your Outlook to the same version as mine(Version 2007 Build 13029.20460) or higher and see if the problem can be resolved.
If the issue still exists, as I know, there could be some add-ins in your Outlook client that cause this issue, so it is suggested to start your Outlook in safe mode (Press Win + R, type “outlook /safe”, press Enter.) and see if the issue continues. Also, after the upgrade, residual files in Outlook may cause Outlook errors. In order to eliminate this factor, please try to completely uninstall your Outlook and reinstall the latest version of Outlook to see if it works.
Hope this can be helpful.
If the response is helpful, please click "Accept Answer" and upvote it.