Important German phoneme missing

I have built and trained several German voices - and they sound pretty great.
What spoils the experience is that at least one important phoneme is missing completely:

Words like "ich" or "nicht" are not pronounced with the correct fricative, but are substituted by an English sounding [sh] sound.

Sadly that destroys all words with that phoneme at the moment, and it occures in many common words and expressions.

Is there any chance to change this soon?

It makes otherwise great voices completely useless.