Has this glitched on anyone else? please help
 

I have to japanese version and the game glitched on me. In mIssIon 8 chapter 2 after first set of guys someone has to appear on the turrets above. Its supposed to be a side quest to kill him for 25k. This guy never appears for me and if I try to complete the level I am short 10k for the gold medal. I tried to clear my system cache, but still nothing.
Any Advice whAt I cAn do?
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