anyone got experience lost inventory when you send in FBA?

We have multiple ASINs with this issue, but for one particular ASIN, it happens about 70% of the time.

Once it reaches the Amazon warehouse, they lose it.

We asked Seller Support, but they haven’t been helpful.

In one case, we sent a shipment that got lost; they approved a reimbursement, but it never happened. We’ve opened multiple cases, referred to the same case, and submitted all the documents from the previous one. Then it turned into a cold case, always ending up with Amazon replying with a “pending” mode.