Hi Tom,
A single Registration, i.e. what is memorized on one of the registration buttons 1 - 10, is comparable to a snapshot of the current panel settings. You can load a style manually at any time (also directly after loading a registration bank and activating a registration from it) and of course also manually set voices for the keyboard parts (Right1-3, Left). Or you can use the OTS of the loaded style. If you want the style's OTS to be switched automatically (depending on the Main Variation used), make sure that OTS LINK is switched ON. (When working with registrations, OTS LINK should normally be switched OFF, since the current Main Variation and, if desired, an Intro, Fill-in or an Ending are memorized anyway on each Registration button (1 - 10).
The keyboard (in your case the Genos) "remembers" the last used Registration Bank even after a restart and loads it automatically. However, no registration is loaded from it, i.e. no Registration button (1 - 10) is activated. You can always, as described above, simply load a style manually, load keyboard voices manually or activate one of the OTS and play as usual, regardless of which registration bank is loaded in the background (and therefore shown in the display). As long as you do not press any of the Registration buttons (1 - 10), the Registration Memory will not affect your performance.
Hope this helps!
Best regards,
Chris