You should log a call with the support team.
I am preparing to update my server from 10.3.1 > 10.6. Did you ever figure out what the issue was? Do you have a step by step guide that Orion provided?
Remote to whatever server Orion is installed on and go to Orion Service Manager, turn everything off and back on.
I didn't have the IIS issue but I did get the engine issue, make sure you let your team know (if you work with a team) that you'll be shutting down the services on that server so potentially you won't be getting any messages if a server were to go down.
Hopefully that helps!