My post applied to the default, hard-coded, BRUSH
mixes of various tiles as stated and NOT your by hand mixes of tertiles. Now that I'm home and able to pull up FlaMe I can see Tile #27 is not
used in any of those hardcoded brush mixes so it has to be an improper re-assignment as Mysterium suggested which I just confirmed by re-assigning #27 and it being impassable in game.
("Cliff Angle" applies to using cliff brushes... if you are doing by elevation brushes, then appliying cliff tertile by hand, you have way, way, more effect lattitude. Just another pointer.)
If you wanna re-assign cliff to non-cliff tiles that are also used in hard-coded brush mixes
then my first post explains how to do it and achieve a wide variety of cliff visuals without creating PF/PW anomaly conflicts and so my reiteration here rather than let it go as the original post had no utilitarian value going forward for other map makers, as seems the direction this has otherwise landed. Now, if my explanation is still lacking towards full comprehension, i'd be willing to give it another shot as to my knowledge, this significant issue has not been addressed anywhere else.