I don’t know if this will be simple to fix, but here it is for the team’s information. It concerns the Mac version of Dorico 3.5.12, in the Edit menu. It doesn’t affect the operation of Dorico, but I was a bit perplexed as to why selecting the menu items worked but using the displayed key commands didn’t. As well as displaying the icons for the Option and Command keys, the menu items for Go To Previous Flow and Go To Next Flow display the Up Arrow and Down Arrow icons instead of the Page Up and Page Down icons respectively.
The key commands as displayed there are actually those used for Raise Pitch by Octave and Lower Pitch by Octave. Once I realised that, everything became clearer. In Preferences > Key Commands, they are displayed correctly.