Pending Sale Issues

Can anyone provide insight on why I'm having sales revert back to in-stock while pending? I've made a number of sales as of late sit in pending status which makes sense because they are extended window FBA sales. These sales after a week have reverted back to my inventory while still pending. As of yesterday I had a sale and within a hour went back to in-stock while still pending. Just now I made a sale which is pending yet hasn't even been stripped from my active at all. I'm at a loss if I should start adjusting this inventory or let it alone to complete the sale.