[theducks]

Originally Posted by eschwartz

Now I see the problem.

Titlecasing ignores words that have capitals in the middle of the word (unless the whole thing is uppercased). Try titlecasing "ChaPter".

See:

src/calibre/utils/titlecase.py line 71

        if INLINE_PERIOD.search(word) or UC_ELSEWHERE.match(word):
            line.append(word)
            continue

I originally took you at your word and tried to replace "Some text."

Case changing (when mixed) has been problematic for me from way back in the DOS days.

I always Lowered, then set the desired case