Multichannel sends

We are producing a largeish ambisonics piece in Ardour 3.3 (Ubuntu 13.04) and there are problems with using multichannel sends.
I’d like to use jconvolver in ambisonics mode to provide some reverb. So I set up external 8-channel sends sitting behind the ambisonics panners (3rd order panners by Jörn Nettingsmeier) to route the channels into jconvolver and routed them back via another track.
It worked at first, then it broke and the sends only put out 2 channels of the 8 channels that come out of the ambisonics panners.
Then I tried setting up an 8-channel aux bus with jconvolver as an insert and internal aux sends sitting behind the panners. Still the same problem: Only two channels get sent (not the first two, but some other two).

I already asked on IRC where Paul wrote that it sounded like a bug.

Now I’d like to know, if there is any way to reset the channels to get it working again. Maybe by doing some xml surgery? Any ideas are welcome.
We already have lots of work invested in automation of ambisonics positions, so setting up a new session would be a desaster. Or is there a way to export/import tracks with automation data?