I'm unsuccessfully trying to buy a one-way Y-fare ticket with the OnePass 5% off code. Even if I specify No Restrictions or "Y" class, the system still gives me H or K class (neither refundable) if I use the OnePass code.

I tried to select the flight w/o using the code, and was able to get a Y class seat. I then clicked on the button to apply the 5% discount. Now I'm looking at a purchase screen that has an H fare (non-refundable) but with the "Upgrade Elite Y fare" label?

Here's the screen image showing the H "upgrade elite" fare.

Sorry if has been discussed before; I tried to search and found nothing.