Samsung Pay Errors at Payment Terminal Galaxy S7

[saintfisher427]

For some reason I sometimes get errors at the payment terminal when trying to use cards through Samsung Pay. The error I receive is along the same lines at different places, saying the card must be inserted. From what I'm told at the stores, none of them are NFC compatible, but they do have active chip card readers. Since I'm assuming Samsung Pay's fake card numbers are non-chip numbers, it should use the MST function. The real kicker it does actually work at these stores sometimes. I've used it no problem on the same registers, while other times it tells me the card must be inserted. The card readers read it almost immediately after my finger is scanned, but whether it goes through with no issues or gives me this error just seems to be chance. I work at one of the stores and tested it a bunch of times. I tried like 4 times in a row, received the error, then it decided to work once, then I cleared and tried it again, but it wouldn't work again after another few attempts.

Things I've tried:
Using different terminal - doesn't seem to make a difference
Removing case - doesn't seem to make a difference
Using different cards - doesn't seem to make a difference