I have mail-enabled a library and I've made the PowerShell changes to my Sharepoint 2019 on-premise server. When I start my workflow manually, it completes fine. However, when I start it when an item is created from the incoming email, I get, "Failed to start workflow. Failed to open a connection to the Nintex Workflow configuration database".
I have verified that the app pool identity has the WSS_Content_Application_Pools user mapping on the Nintex database in SQL Server. I've restarted the server and the workflow is still giving me this error. What else can I check?