I didn’t find articles from Microsoft. But this article was provided by Microsoft MVP.
According to this article, we can’t change from an auto-generated Outbound Signing Certificate to a CA issued Outbound Signing Certificate. This is a significant constraint of Workflow Manager configuration, even though we can update the certificate, workflows will get “stuck” in their initial stage after doing so, as the Workflow Manager farm thinks it’s an auto-generated certificate.
If an Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.