My installed version Orion Platform, NCM, NPM, NTA HF1, UDT: 2020.2.1
I'm trying to create a custom property that only applies to APC UPS models. I create a custom property, use Nodes as object type. Give it a random name and for the sake of testing I keep all the checkmarks on under Usage.
The next tab I select nodes. I only select APC and leave my cisco gear unchecked. I then select all nodes and submit.

In the end the Test field comes up for all my nodes regardless of Vendor. Is this how it is supposed to be used?