"All" is probably a misnomer there but the VAST majority operate out of A.

checked bag fee waived with reward ticket?
 

I have a continental one pass credit card. I booked a reward flight, so technically I didn't "purchase" the ticket with my card. The reward was booked on continental.com but the flight was United. When I went to the UA counter to check in, they wouldn't waive the baggage fee, even after showing them my credit card. I think they didn't abide by their own rules, and I should not have paid the baggage fee.

First of all, welcome to FT!

Second, this specific thread is not the best place to post, as you won't get too many responses.

Third, the issue of waiving the bag fee for OnePass Plus/Explorer and Presidential Plus card-holders on reward tickets is discussed in numerous places here. Some have had success when paying the taxes/fees with the card; others by swiping the card to pull up the reservation; others by simply showing the card; and still yet others have had the fee automatically waived. All that has been with CO-operated flights. It's harder with UA-operated flights as it's a different system, and therefore possible it simply didn't show up.
Try speaking to UA now, post-flight, and request a refund.

FAQ Thread Post #24
 

Add to the list:

CLT Yes
GEG No
JFK Yes
SMF No