I also got the 012-1206-403 error repeatedly when trying to stream ABC on Roku using a DirectTV / ATTUverse account. After trying to reset maybe a dozen times, I found a number for ABC app support and called. They told me the missing key: Before resetting your TV Provider in the Account area, clear the browsing history on the device you used to activate ABC originally. That worked for me, although it only worked when I selected “DirectTV” as my TV Provider rather than ATTUverse.
I also got the 012-1206-403 error repeatedly when trying to stream ABC on Roku using a DirectTV / ATTUverse account. After trying to reset maybe a dozen times, I found a number for ABC app support and called. They told me the missing key: Before resetting your TV Provider in the Account area, clear the browsing history on the device you used to activate ABC originally. That worked for me, although it only worked when I selected “DirectTV” as my TV Provider rather than ATTUverse.