UPDATE:
I have created a new multi-notification macro to be kicked off by the SLA upcoming/missed event we have set. The macro uses a custom email template that takes advantage of the built in CA variables to display unique information relating to the ticket such as assignee (@{call_req_id.assignee.combo_name}) and status(@{call_req_id.status.sym}). The issue we are now running into is that these variables are not returning any information when the email is sent this way. Is there another set of unique variables that we need to use to pull the information, a setting that must be in place, or will we need to create a different macro altogether?
We have successfully done this before with emails being triggered by Change status updates and workflow conditions being met which is what the SLA macro was modeled after. I have also tested the notification using the OOTB email and the same issue occurs.