Personally I think the biggest problem is the rewrite FFG did to the Declare Target step in the TFA Rules Reference, specifically the last bullet point of page 4. They've effectively nerfed or broken more than one ability with that rewrite.
I think the target should become the "defender" before the costs are paid and that is the moment it's "declared" as the "defender", but only if the attack is valid (in range and arc) for the weapon chosen. And if you can't carry through with the attack because of a blocking ability of some sort, then none of those steps happened, much the same as an action that can't be taken, didn't happen. But that's just my opinion based on my own hinky logic.