Disappearing Hairpins and Slurs

Something I've been noticing for a while in a piece I've been writing is that when I look at the score, everything looks perfectly normal. But when I go into any of the parts, all the crescendos, diminuendos, and slurs are missing. When I add them back into the part, it puts another slur on top of the one that was already there on the score. Another thing that happens less often is the music from one part will get duplicated onto a different part. Is there any fix for this that doesn't involve me manually removing all the hairpins and slurs from my score and putting them back in one by one for each and every part?