my right side menu open/close button disappeared

[happyhafer]

i was reading a chapter with wider pages and closed the right side menu to open space.
until now there was a button to open the menu back open, but that button has disappeared and now i have no means of opening the menu i can find.
i know there is supposed to be a hotkey to do that, but i have long since forgotten it and can't find any post about it either.
does anyone know the hotkey or how to access the reader menu options outside of chapters?

 

[HelperHand]

but i have long since forgotten it and can't find any post about it either.
does anyone know the hotkey

The hotkey is "m" or click the center of the image, also the reader settings only display in a chapter, any info about the browser for other to check if they also have the same issue?

 

[happyhafer]

thanks!
clicking the center was literally the only thing i didn't know to try...

 

[happyhafer]

i am using firefox.
and i already tried disabling adblockers and noscript, didn't do anything noticeably.

 

[happyhafer]

...ah, found the source of the issue in the reader settings.
''Show menu button when the menu is pinned and the header is hidden''
i don't know since when but it seems this checkbox was unchecked/disabled for me.