Steps to Reproduce:
EITHER:
A. Hold any undyed leather armor piece
B. Drop any undyed leather armor piece
C. Put any undyed leather armor piece in an Item Frame

Expected Results:
Undyed Leather Armor renders undyed anywhere

Observed Results:
Undyed Leather Armor renders as if it were dyed brown in your hand, on the ground, and in item frames.

-Side note: It appears normally in your hotbar.