We currently have a Known issue where you will need 1 Custom Property each setup for Nodes, Interfaces, and Volumes, you will not need to have any information in the Property, just one added.
To create a property with Custom Property Editor:
1. Click Start > All Programs > SolarWinds Orion > Grouping and Access Control > Custom Property Editor.
2. Click Add Custom Property.
3. If you want to add predefined properties, complete the following procedure:
a. Select Add Predefined Properties.
b. Check Show Advanced Properties to view additional predefined properties.
c. Check the properties you want to add (select 1 Custom Property each for Nodes, Interfaces, and Volumes) and then click OK.
After you have completed the above, please Retest the Unmanage Utility again.
Thanks Sean, already found that solution and did not work for me. I also see the error message i get is different than the known bug