Override Alarm Display Path on UDT Member?

Hi all - I've got a UDT defined in Ignition (ver 8.1.26), with one of the UDT members being a boolean OPC tag called "Status". I've defined an alarm on that tag (triggered when the tag = 1), and have defined the Display Path within that alarm to be dynamically generated based on certain parameters of that UDT.

Specifically, my Display path is set to be {TagName}+" "+{[.]Description}+" Alarm"
(I have a parameter "TagName" that I use instead of the instance name of the UDT instance, and the UDT has a String member called "Description")

This works 99% of the time for what I want - the display path triggered will match exactly what I want to the alarm to say. However, for that 1% I was hoping that I could manually go into the tag instance and change override the alarm display path - but it seems like I'm either doing something wrong or something forbidden.

Is there a way for me to change that alarm display path? What I've been trying to do is expand my UDT instance in the tag browser, drill down to the alarm display path, and type something new in there. However, I get a "Bad_Unsupported" popup when I do that. If I double-click on the tag in the tag browser, all the alarm details are greyed out.

Hoping there's a solution - thanks in advance!