Pinyin mode does not put diacritics on top of vowels anymore

[Hellstorm]

Hello,

the pinyin mode worked in the past, but currently (don't know since which version), it does not work anymore.

for example, I want to have the word “nǐ”, so I press ni and the ˇ key, but then I only get “niˇ”.

Can you please fix this? Thanks!