Inventory becoming unsellable

Over the last month I’ve had 4 different items become unsellable while being stored (sent to amazon weeks ago) and I’ve gotten emails saying they are in unsellable condition. To the best of my knowledge they haven’t been refunded. What causes this? Surely amazon has to reburise me for the damage that’s clearly happening in the warehouses ? Some of the items are wrapped up others are boxed up and other items I’ve sent in multiple items.