I'm surprised they paid you before they closed the job out. When I had an issue, it sat a couple days with a question mark while they sorted it out. I think once they paid you as if the job was accepted, it was their mistake. Is your negative balance with Field Agent? Like you have to take more jobs to work it off?
I've never cashed out on the same day, but also I don't like to let anything sit too long.
I don't think I would count blank tags, because there is no way to know what is supposed to be there. If it was supposed to be a double-facing, split what is beside it and nothing is out of stock.
Also, it sounds like they could have corrected it from the photo, doesn't it? Then just ding your score and fix the instructions.
Former mystery shopper, current merchandiser.