When you Initially create Expenditure Batch , Batch will be in Working status, later when click on Submit, Expenditure Batch status gets changed to "Submitted" until you release it doesn't get "Released"
Ideally you can choose "Unreleased" status from the poplist in the find Expenditure batches window, system retrives all expenditure batches both which are in working and submitted status
Expenditure Batches which are in "Submitted" or "Working" are considered UNRELEASED batches.
But to release a Batch first the batch status should be in "Submitted" then only we can release it.
There are No concurrent process available to Un-release a batch.