Firmware 4.23.15505
This update changes large parts of how the navigation works. While NickelMenu is still safe to use and will still add menu items to the other (library, browser, reader) menus, items added to the main menu will not appear. In addition, actions related to navigation (mainly nickel_open and nickel_misc:home) may not work correctly.
I will be working on an update to NickelMenu to re-add support for the main menu sometime this week. I will probably do it one (or both) of two ways: adding an entirely new menu which appears when pressing the new clock in the top-left, or adding items to the "More" tab on the new bottom navigation.
See the
firmware thread for more details.