I just tried doing a custom face with watch styler and it doesn't work.
my files----all-----device storage----android----data----kr.co.omnicon.android.appcessory.watchstylermanager.gear3.s
then open the saved design folder and delete the image file
This should do the trick. When you design your watch face do you rename it or leave it with the #'s? Whichever way when you get to the folder it should look like this. Depending on how many faces you made then just open the folder for the face you created and delete the image file that shows the finished face you made and that's it. It should be 2 images one of the background you selected and one that's completed. The completed pic is the one you delete. Then go to the gear app select the watch styler then the watch face and your good.