Ok, so I'm not totally clear on your results.
The troubleshooting tool results look exactly correct. If you are seeing the OMSA version (and you are), then it will get discovered and classified as a server if your discovery wizard has SNMP checked with the right, case-senstiive, SNMP community name....and make sure all other protocols are not selected.
If it has been incorrectly discovered and classified once, be sure to right-click delete the server before running the discovery range again.
Often it helps to create a discovery range with a single IP address of the problematic box. That might make it easier to debug if it is not getting classified as a server.