Korean text typing error

In recent version (maybe 9.6~), Korean character at the first position of line suffers disassemble error. For example, when typing ‘강물’ (in order of ㄱ + ㅏ + ㅇ + ㅁ + ㅜ + ㄹ), Textastic force to represent ‘ㄱㅏㅇ물’. There is no way to assemble it; the only (temporary) solution is add a whitespace or other character before typing, and delete it later.