Xinity rewards Amazon bookshelf 8-20

I successfully redeemed the Amazon Bookshelf offer for "One Last Summer Read" yesterday, August 20.  And I have the promo code.  I waited until later to redeem it though because it is valid through August 27 & there were so many issues last week with the Amazon credits. 

When I click on the link, it opens up the "One Last Summer Read Bookshelf".  However, when I put in my promo code, I get a message that "Voucher was applied to another Amazon account. Login with the correct Amazon account to use the voucher."  

I definitely didn't apply it to a different Amazon account because I only have one.  And the voucher is definitely not applied to my account.

Any suggestions?