Just tested, still not working.
Expected: □ ■ □ ■
■ □ ■ □
□ ■ □ ■
■ □ ■ □, instead got: □ ■ □ ■
■ □ ■ □
□ ■ □ ■
■ □ ■ □

Would you like to see my code?

I too have the same problem as MacInnes, my expected and received outputs are the same. I even used split('') to see if there are any whitespaces but none that I can see.

If checkerboard(4)

My array to see if there any whitespaces at the end:

["□", " ", "■", " ", "□", " ", "■", "\n", "■", " ", "□", …]

Not sure where to go from here...