Bikerjulio- I indeed have a set of cables with ferrules on the end of them. In fact I've gone through three sets of cables all in original packaging bought from bike shops. Two of them had cables with ferrules on them and one set did not.
Two of them are 10S and one is 11S which works fine on 10S if you put the ferrules for your old cableset on the new one wherever they're missing.
The der. cables had their ferrules crimped on on one side (the shifter IIRC) and a loose fitting one on the cable stop end.
But I'm sure that's not your problem here.
Two more things that fit the description of your problem:
1/ The large flat coiled spring in the shifter has been put the wrong way around. The way the shifter looks it is actually counterintuitive to mount it the correct way. Sympton: all works well shifting up but when shifting down the coiled is not sufficiently tensioned and after a few shifts downwards it hangs inbetween cogs.
2/ The cassette spacers of (I think) cog 6 and 7 are in reversed position. Again an easy mistake to make which will make it impossible to perfectly align all shifts. it will either under- or overshift. Overshift is caused by too high cable tension (since you try to get it to shift up correctly) causing hesitant downshift. Undershift will cause chain rattle onthe middle cogs mostly.
Hope this helps,