Actually, creating cross-staff notation in Dorico is very straightforward. But something strange happened recently:
Even more surprising, however, is the result I got in the following bar (which was what I had expected):
Does anyone have an idea what might be causing this? Or to put it another way: how can I force one version or the other?
For the first example, what’s happening if, once cross-staff is done, you select any note of the first beamed group (the first eight 32ds), right-click > Stem > Remove forced stem?
If the stem direction has been forced at some point (by pressing F), the override will remain in case of cross-staff, so the beam won’t be centered between the staves.
Wow - you are the greatest. I had already suspected that I had accidentally pressed the wrong key, but I didn’t know which one… 
Thank you, thank you!