I've tried several credit cards with the same result. This kind of seems like bait-and-switch, because the only way forward now is to pay via deducting it from my federal return. However, that's an extra fee I don't need to or want to pay.
I've already called customer service where I was on hold for an hour, not getting through to an agent, with the interactive voice response system simply hanging up on me. I'm on another phone call to try to resolve this, on hold yet again, this time for 36 minutes, so far. If I simply get hung up on again, this will not go well.
Right now, I am unhappy with this service. If I can't get this resolved, I'm going to end up using a competitor's service next year.
Update: I did *finally* get through to customer service. There is a procedure where you can go into Turbotax Deluxe 2018, go to the part where you try to pay by credit card, a window pops up, and an obscure "click here if you've been having problems" link appears that takes you to a set of instructions involving calling customer service and providing a serial number to them. They then use this to find your failed credit card transaction, manually fix it/run it through again, then they provide you with a confirmation number you copy/paste into the software, letting the e-file transaction to go forward. Using this procedure, I was able to e-file.
I am satisfied with the outcome and will use Turbotax's services in the future.