We've definitely seen it happen to others where if we wind up making a bunch of individual charges one after the other the cc will start blocking us a few charges in -- though it doesn't appear to be common enough for us to have done something about it. Mostly, I think, attributed to the tragedy of the mega-derail being reasonably uncommon. It definitely happens from time to time, but it's not suuper regular.
Anyway, if that's the state of things with that credit card there's probably not much, if anything, we can do from our end, but if you call your bank it is possible that they may be able to unflag our domain or whatever. I think that a few people have had success with that in the past.
Hearing if there are more instances of this though would be super useful! Maybe we should be prioritizing batching payments? So if anyone else has run into this, it'd be great to hear about! Also, knowing what type of card might be relevant info -- like I think that American Express is more paranoid about potential fraud than some of the other brands.