This could be user error/forgetfulness...
The client user could not reverse any documents - which upon investigation was because they were already reversed!
However she says that she DID NOT press 'save' at any time.
My understanding (and my subsequent testing in QA) says that no way does it reverse until you 'select' the desired documents, then 'save'.
Does anyone disagree with me?
She is convinced that she did not 'save', I asked her to confirm this several times.