Accents (for vowels) have disappeared

I am running OS High Sierra 10.13.4. Following the most recent software update, my ability to select accents for letters has disappeared. If, for example, I press the letter e on the keyboard and hold it down, it simply repeats the letter e. I no longer see the pop-up menu which proposes e acute, e grave, e with two dots etc. How do I get this back?

I use the UK keyboard as I mainly write in English , but I often need to write in French and German and need the accents