You would do best to call Yamaha Customer Support - Not aware of any Looping bug or the firmware you mention - they will have a record.

To expand on this, the looping bug drops a fraction of the first beat when changing patterns during song mode. When I first purchased the AN200 in 2001 i contacted Yamaha and they never got back to me, only saying that it needed a software update.

Since then i've downloaded two internal software updates from 2001 and 2005 - both claiming to be v1.03. Nobody seems to know whether they work or not!