Release Committed Stock

If an eBay order is not completed the stock will remain allocated until it is released. 
To release this stock you can open an unpaid item dispute and upon dispute closure the stock will refresh automatically.

For manual release go ebay > transactions > find incomplete transaction using filters > tick the relevant transaction > at bottom of page click 'Bulk Release Reserve Stock' as per below: 

Alternatively you can find these transactions in the SKU by going to 'Stock Control' and selecting 'eBay Transactions' and reviewing all the committed stock from here.