Take Offline

Yes, there's a 7-level limit on how deeply posts can be nested. You've already found the standard work-around: repeatedly replying to the sixth-level post, and including the name of who you're responding to in the Subject.

These two are old sparring partners. As tbmay says, most of us just ignore them, scrolling down until we reach the next branch. Peacemaking is futile; they'll never work and play well together.