Is the vectorial scale set the same as it was in 9?
I'm just wondering if there was a bug in the fill transition somehow. The magnification is just a zoom in/out, so it's not that important. I would look at the scale of the fills.... beyond that I don't have any ideas. I know I have brought over several files from AC9 and not had this problem.... yet.
I also had a problem with AC10 fills. I just printed a section. The siding and shingles printed correctly(vectorial), but the wall fills (%25) printed out like bitmap.
AC19(9001), 27" iMac i7, 12 gb ram, ATI Radeon HD 4850 512mb, OS 10.12.6
I thought the percentage fills have always been dot patterns, bit map or not. I don't recommend them. I use grey pens instead. PDFs shrink to a fraction of the size immediately, print faster, and scale better.