There are several issues related to this:

https://github.com/e14n/pump.io/issues/479

https://github.com/e14n/pump.io/issues/765

https://github.com/e14n/pump.io/issues/775

https://github.com/e14n/pump.io/issues/883

I'm afraid listing the issues is all that I can do about this, even I don't understand very well where is the problem, I just can confirm that "non public" + shares + replies don't mix well in pump.io right now...