Japanese Analysis Text Problems

Hello! I'm generating japanese lipsync and I found that with mixed japanese analysis text (Kanji, Hiragana and Katakana) the lipsync animation is stopping sometimes and it's irregular.
I translated the text to only Hiragana and Katakana and those two seem to work okay. I also tried Rōmaji, but I couldn't load the text file and I had to copy the text manually.
Is there a preferred sign type that should always work? What do you suggest?