IPA does leave a residue.
I still use it, but use a cloth that only one side is for cleaning the plate, and the other side I sorta buff the plate again to remove most of that residue. Works for me.
I use glue on the smooth with ABS or PETG-HF. Makes prints alot easier to remove from the plate sometimes. I just put a little glue on the plate and wipe with a slightly damp (sometimes dry when I’m in a hurry) cloth. Spreads it evenly over where I need it.
Best way to test is is with the smooth plate, easier to see anything on the plate.