I was thinking of string wear but also the shock caused by the string hitting a smaller section rather that the whole groove or even clearing it. It is not a sharp angle and I did have a mistake. in the first post. The BOW is pushing the string to a slight angle. None of my factory long bows make contact there. Just an observation and rather difficult for me to explain but I think you got it.
Good Luck. Just a little more angle or radius to clear it.Ken