CEC Adapter

What makes you think that long press Ok is context menu?was it working before?

In most CEC instances there is no CEC context button enabled by default and all you have to do is map a button on your remote...Use a button that you don't normally use for anything else kodi related...

Start by installing Keymap Editor addon from kodi repo..and map a global-navigation-context menu button that works anywhere in kodi unrelevant of what window you are on..