That is the way asterisk works with recordings. Only in recent asterisk versions there are provisions to mantain recordings after call masquerading, but that has to be done via dialplan and variables.
When you pickup a call from a queue, you are actually TAKING THE CALL OUT OF THE QUEUE APPLICATION.
That means, not only the recording is lost, but also you are creating a new call outside the queue, so the queue logger will report the call as ABANDONED.
None of this is a bug in FOP2, but a feature in Asterisk.
Best regards,