If you ask me, you have an geometry issue. because I had have the same problem.
I also has had the blades even when at zero pitch but when at 8 degree at 1 set of blades the other set was something differed aproxx 10 degree and the blades make a lot of noise and poor stopping power.
The cause in my case was not a proper geometry between the two blade sets and the sulution was to make the linkage between the blades parallel with the tail shaft.
Just by adding spacers (two M2 nuts) between the blade grips pivots see photo,
and shorten the other blade grips pivots by apros 1.5mm
Now the blades are staying nearly paralleled between the two sets and the noise are (almost) gone by max stroke with hard rudder, but now the stopping power are enough but keep the head speed high as possible.
Now its OK
Then your X tail can not make it to the real scale degree because your linkage will bind then so you have to make it the best out of two given facts
The next photo was the old setup without the spacers giving the bad results.
You can easily seen that the linkage are not parallel at all with the tail shaft.
Hope this will answer your question Jay,
Regards from Holland,