Notification Pipeline expressions return null

I have an email notification pipeline that works just fine, but I want to control which alarms get sent out based on the value of a separate tag than the alarm itself. However, every time I attempt to read the value of a tag based on the tag path I get null. Also, I can’t execute runScript() in a Set Property block. I get the same null result.

I can only assume that for some reason these expressions cannot run inside of a notification pipeline, but I can’t find anywhere in the documentation that actually states what expressions are or aren’t valid. So I guess I have two and a half questions:

  1. Is it true that expressions which depend on outside tags do not work in the expression binding in a notification pipeline?
    1a. If the answer to 1 is yes, would someone please explain why this was necessary? Without this ability it seems I have to go through my entire project and add binding to every single alarm tag.
  2. Is there a list of which expressions are valid and which are not? Guessing seems like a good way to waste a lot of time.

Edit: I realized I should include that I am running Ignition version 7.6.6 on Java version 6 update 45.