Originally I had ASIO 1, 2, 5, 6, 3, 4 in the routing table, and then the Ls and Rs channels went to ASIO 5, 6 (alongside C, LFE) instead of 3, 4 (alongside Ls, Rs).
So I just did another experiment. I specified “unused” for C and LFE (so the table read ASIO 1, 2, unused, unused, 3, 4); then my four output channels went to the four specified ASIO channels as required. But I previously (in 9.5) had C, LFE specified as ASIO 5, 6 because sometimes I had a six-channel montage - and there was no need to keep changing the routing for different montages because the audio followed the channel name, not just the order.
Now, for my part, I have no interest in these channel names, as they are meaningless for my audio; not least the signals have different meanings at the input to the montage and at the output, because a VST has done ambisonic matrixing on them in between. If in the future the routing works without them (the names) I will be just as happy. Indeed, I am happy enough now that I can see how it’s working in the present code. I raised the matter because (a) if someone else is relying on the routing working as it used to, they could also get caught out, and (b) if in the future you retain the different naming schemes for the various DVD schemes with the same number of channels, it needs to work again as before.
Though honestly I’d do it entirely differently… I would simply route the n channels of the montage/multichannel file to the destinations specified in the first n entries of the routing table. Different DVD channel naming schemes (required for the loudspeaker mask) could be specified on top of that without changing the routing. Of course, it may even be that you are in the process of changing over to that arrangement, and that I’ve just caught you out in the middle of the alterations!