How often do items get out of stock? about analytics HOT 3 OPEN

The element in event we wish to track has class=alert-box:

with text:
An item in your cart has become unavailable. Please update the selected quantities.

On URL:
/cart

from analytics.

Ok, I've found this configuration to work in staging:

1. A goal

2. A view trigger:
   

3. A tag pointing to the Goal created step 1) and the trigger set up in step 2)

This can then be seen on the Goals results:

from analytics.

Ok, this is now working for UK-prod:

The cool thing about it, is we can see which shop is triggering this the most:

from analytics.