Character accent menu only appears for some letters Although when I hold down 'e' the accent menu appears fine, if I hold down 'r' it does not. This is not due to no accents existing for r - the character I am trying to get is ' ř ' - as I have had the accent menu appear for it before. I do not know what has changed between my previous usage and my current that should have caused the menu to disappear.
 Help would be much appreciated.

(I am currently using a MacBook Air running OSX Yosemite 10.10.5)
There are no accents on "r" on my El Capitan with the US keyboard, and I don't remember ever seeing ř on it or any others, except for Czech, which I think is the only language that uses it.