Thanks for the reply. I went ahead and did both sides at once this time and they seem to have been accepted.
They were the correct cards and maybe there was no error message for that so that is what was chosen.
If both the back and front have to be done at the same time, I think the documentation should be updated to indicate that.
I also had a question about VARS. If the variation is only on one side of the card then why can't we use the side that is not a variation for all of them instead of having to scan and upload that multiple times?