Kieran, I think you missed the point there slightly. This is obviously a bug in A2B; it doesn't need a configuration option, it needs to be fixed.
Amaterasu, sorry I didn't notice your post previously. I have seen symptoms like this, but I'm not convinced our assessment of the root cause of the problem tallies. I last dealt with this issue around 6 months ago, so my memory is very hazy but I seem to remember I fixed the bug. I could be wrong though.
I've got to go out now, and I can't quickly find any relevant threads or bugs; try searching the bug tracker (then this forum) yourself.
Added after 16 minutes: My ride hasn't yet arrived which gave me the opportunity to search some more on your behalf.
Behold
the solution. Of course, if you'd upgraded A2B to something more recent than v1.3.0 you wouldn't be seeing this problem now.