My product won't create the FBA shipment

We have an ASIN that won't allow us to create a shipment, and we encountered an issue when trying to follow up on this problem. After consulting Amazon customer service, they informed us that our products are restricted. However, they were unable to provide a reason for the restriction or offer an effective solution. We feel very helpless, as multiple cases we've opened have not resolved the issue. Has anyone else experienced a similar situation?