While the two bookings on the same flight may have been the problem, the cause is likely to be the fact that you can no longer have a confirmed award segment on an award itn that has one wait-listed segment.

If you book a multi-segment itn, with one wait-listed sector, all sectors are wait-listed. The email confirm does not show this, but trying a dummy booking and looking it up on sq.com will confirms this.

BTW, you can no longer cancel wait-listed or confirmed redemption bookings online.