Timed Text file includes events with misspellings or incorrect punctuation.
Use the spell checking function within your subtitling software, prior to export, to catch any typos.
If you encounter this issue, simply go through and correct the typos highlighted. We would recommend that you go through the entire file and ensure there are no additional typos. Also ensure that only characters from the language being translated into are included. For example a Simplified Chinese timed text asset can not contain Traditional Chinese characters.