Dorico Pro 3.5.10 on Mac.
I assigned the shortcut Alt+: to Split Beam, and Alt+Shift+: to Beam Together.
They didn’t work. I saw that they were put in the kGlobal context in the preference file, and moved them to the kWrite context. I was careful to put the comma where needed, and remove it at the end of the list.
Still, the new shortcuts are not working. They don’t overlap with other commands.
P.S: I noticed that Dorico is still creating a “Dorico 3” folder inside the Application Support/Steinberg/ folder. It stores the backup files there.