Years back when I first was approved for the BOA Travel Rewards, I had 0 banking relationship with them, so as others have said that likely isn't the issue. I concur with all the great advice on gardening, that's probably the best route to take for a few months or more.
I have had a checking and savings account with BOA for over 20 years, and recently was denied a card. I get offers to apply all the time, and I finally applied and Boom...Denied. Thanks for the hard pull for a no.