Oops! Sorry, Steve @scook- I must not have email alerts turned on for the new forum, so I didn't know that you had replied. Thanks for your reply.
I no longer can see any way to select a custom layout, although I can switch freely between the three "sort by" categories. I can open, edit, save the custom layouts via "manage layouts" (which opens Cakewalk Plug-in Manager). But there is no longer any way to select a custom layout. I can't even remember how that used to happen - it was a reflex, like so many things in familiar software.
I've checked Preferences and I can't see anything that seems relevant. The File Location setting is pointing to the correct folder.
With your encyclopaedic knowledge of the inner workings, can you think of anything I can try?