I had the same problem over the past few days with standard VGCs purchased during the recent Staples and OM/OD deals. After some back and forth with Plastiq and GCM, I got this email from Plastiq this afternoon. With a few grand in VGCs in low denominations and no nearby Wally World, I have to say this is a concern for me.

Hello there,

We have taken a look at your payment and see that Metabank is rejecting our payments as they are flagging them as not an acceptable category. This means that they have taken a stand to not accept Plastiq payments. We will be reaching out to them to see why they have taken this aggressive stance since we do allow credit, debit, prepaid, and gift cards in our system so you can pay all your life bills with us.

I am not sure how long this will take to get resolved but in the meantime, I would recommend that you a different card that is not from them since it only this one card issuer that is not accepting Plastiq payments.

Feel free to let me know if you have any other questions!

Miguel \ Service Team Manager