Trigger Updater When Host Changes

I would like to add a trigger to an updater when the host of a family instance changes (i.e. when an instance attaches to a new host via pick new host).

*filter is just an element filter for FamilyInstance.

I've tried adding a trigger via GetChangeTypeParameter for INSTANCE_FREE_HOST_PARAM, HOST_ID, etc but none have set off the updater. The updater will work for any generic trigger like GetChangeTypeElementAddition, or ChangeTypeAny.

Any ideas why the trigger is not setting off?