Originally Posted by
jsloan
Because nothing will ever show up. EF doesn’t have access to UA’s R inventory, so the alert will never be sent. The best that you can do is to set an alert for I space, as I is generally >= R. But I is even more rare than R is.
That's a pretty darn good reason then. I had a similar experience trying to book J inventory a few years back - turns out EF doesn't understand J either but once I learned to look for I everything worked swimmingly (I set alerts and ended up using them exactly as intended - called UA and bought a Ycabin then used miles to upgrade instantly).
Thanks all!