Brief Synopsis: 

Create a template with any name.

Create an item (within the template) with the following key: net.if.in[\{$SNIFFERNICIP}]

Create a trigger referencing the item (above) with the following information: 

name: {HOST.NAME} - The Lansweeper Sniffer Interface may be having issues. Please investigate.

expression: max(/BIC - Lansweeper Sniffer Network Interface/net.if.in[\{$SNIFFERNICIP}],30m)<"2000"

Do not define the "SNIFFERNICIP" macro on the host or anywhere in the zabbix system.

Expected outcome:  

After some time, the trigger needs to be marked as 'undefined' and a reason needs to specify "Undefined Macro."  The trigger should not be placed into a 'problem' state.

Actual outcome:  The trigger is NOT marked as 'undefined', however the trigger still goes into a problem state (reference screenshot)