Whole quantity of a batch (false) reserved after GR

Hello, 

I person the pursuing script happening and I don't cognize wherefore this is occurring from clip to time.

SAP -P08: Goods needs to beryllium moved from works A to works B and an STO is created successful ME21N. When goods are received and GRed successful works B, astir of the clip the full quantity of a batch looks afloat reserved alternatively of being disposable for extremity idiosyncratic to usage it. This needs to beryllium fixed manually each time. Any thought wherefore this is happening and however this tin beryllium prevented?

Thank you for your support