Alert Composer: Add Filter to only send to employees not contingent workers

Hi There,

Does anyone know of a filter we can add to a Resource Alert so that it only triggers for a particularly System Person Type? For example we have Contingent Workers (contractors) in the system and we want to be able to assign them learning but not trigger the alert.

I tried: ${assignedToUserPersonType} <> 'Contingent Worker' as well as

${assignedToSystemPersonType} <> 'Contingent Worker' but neither were valid.

Appreciate any guidance.

Thanks,

Hannah