For this issue:
We also received a solution from ServiceNow to repair the "Discovery Core [com.snc.discovery.core]" plugin on the instance. The choices for the Discovery type were missing. If this still doesn't work, we were advised to export the missing discovery choice list from an OOB instance.
As recommended, we searched for the plugin, but it was not visible to us because it is only accessible to users with the MAINT role, which customers do not have. Therefore, Support repaired the Discovery Core plugin for us, and it resolved the issue.
