Thank you for following up on this and I apologize for the delayed response!
When it comes to adding certificates in Key Vault issued by non-partnered CAs - I reproduced your issue and noticed that once my certificate is created, it's "enabled" and shows "Completed" when I navigate to the Certificate Operations pane, additionally the "Merge Signed Request" button is greyed out.
Looking at one of my older non-partnered CAs that I created, it looks like everything is working as expected with the Status showing "In Progress".
- Because this looks like a potential bug, I've reached out to the Key Vault team regarding this and will update as soon as possible.
If you have any other questions, please let me know. Thank you for your time and patience throughout this issue.