Bug with alternating time signatures and pick-up bars

I had a quick look through the forum and couldn’t see anything about this so I’m hoping I’m not just doing something wrong.

When I create an alternating 9/8 + 6/8 time signature with a 1/2 beat pick-up, I believe Dorico is counting the pick-up bar as the first time signature, so that the first full bar is actually the second time signature. The attached image should explain it better.

I’m assuming this is not intended behaviour?

I’ve just come across this problem too, and have only found this post relating to it. Writing in the popover “9/8 + 12/8, 1”, I would expect after the initial quaver, the first full bar to be 9/8, but Dorico puts barlines as if the first full bar is 12/8.

Does shifting the full-measure indications solve the problem? “12/8 + 9/8, 1”
It may be that Dorico counts the pickup as representing the first time sig of the pair.

That apparently is the case. So switch your 9/8 and 12/8 in the formula.

If the first full bar is to be 9/8, “12/8 + 9/8, 1” indicates otherwise.

You can be a purist, or you can use what works. Clearly Dorico thinks the pickup measure is a shortened form of the “first” measure in the time signature.

You could also, of course, set the actual time signature of the pickup measure and start your additive times signature in measure 2.