Problems with ifTrunk in alert

When I create an alert and in the Association ruleset uses the type "Port ifTrunk" and set it to not in "access,dot1q,hybrid" it does not match interfaces that has the value set to null, it only matches interfaces with the value set to "" or routed.

I have attached two screenshots of port interface data where the ifTrunk is null or "", and it is only "" that is matching.