I don't know if this has been mentioned yet, but I've been having problems with windows making bricks with most color FX completely disappear, as well as making any overlapping faces appear invisible.
Pictures:
(Normal)
(Through window) Notice how the far plate's side face is invisible due to the adjacent 1x4 plate with pearl FX.
Only glow FX works normally through windows, and undulo works as far as not erasing touching faces, but bricks with undulo are still invisible.