Previously, DP [1,2] in the forum mentioned that Yami counts as grocery with Chase. This month, the OP happened to place two orders—the first one still counted, but by the second one it no longer did. Not sure whether Chase/Yami changed the MCC or if it's just an occasional bug.
This quarter CFF is grocery, so Yami might not be usable for it going forward.
You mentioned that the first order counts but the second one doesn't. Could it be that the two orders have different product types, which leads to different MCCs? For example, food and household goods might fall under different categories. This boundary condition is worth double-checking.
You can start by checking the category code on your recent bill to confirm whether it's Yamibuy as a whole that has changed.
MCC classification can vary by region or card issuer, and even cards from the same bank in different batches may differ. If you really need to shop at Yamibuy, don't rely solely on the CFF grocery category—it's best to pair it with a card that offers a fixed high cashback rate as a fallback, and keep an eye out for Chase's future category adjustment notices.
The most noteworthy detail isn't the second order—it's that if the MCC has changed, all future Yami orders could be affected. I'd suggest holding off on large orders for now: test the current category with a small order, and also check the category description on your credit card statement to confirm whether the change is on Yami's end or Chase's.