ASIN I’ve Sold for Years Just Got Blocked – Suggestions Aren’t Helping

I’ve been selling the same ASIN (B004N84C18) via FBA for years with no issues — and now suddenly, I’m getting blocked from sending it in.

When I try to create a shipment, I get 3 errors:

1. “This product is ineligible for sending to Amazon with a manufacturer barcode.” → I’ve always used manufacturer barcodes for this, so I’m not sure why this is coming up now. I tried switching to Amazon barcodes, but it says the ASIN is ineligible for FBA.
2. “The ASIN has stranded inventory.” → I went to the stranded inventory page, but this sku is not there.
3. “Product is under dangerous goods (hazmat) r*****. The submitted documentation is incomplete.” → Again, this is a product I’ve sold forever without any hazmat issues. I submitted the SDS, but it keeps blocking me from sending to FBA.

I’ve followed all the “Learn More” links, but none of the steps seem to resolve the issue. Anyone else ever dealt with this combo of problems? Any idea how to actually get it fixed or escalated?

Appreciate any help — this is one of my top sellers.