shipping container won't stay one colour

[MORT]

so i just got the new shipping container skin and just tried it out, i wanted to make a full black or white base but it would not stay one colour after changing it with the spraycan. Am i doing something wrong or is this bugged?

[bLz']

build one container, change with spray, upgrade rest , should make it same color.
if it bugs just change 1 extra wall with spray again.
if still doesnt work something is weird.