Mesh upload glitch Please help!

this is what I want to import:

but when I do it looks like this:
image

I have no clue why this is happening and I really need help.
for some reason, it works when I only upload one square though…
image
if you know whats going on, pls help me!

I actually just got it working. I have no clue how on earth something like this happens but when I just went on a different computer, everything was totally fine there. One of the weirdest glitches I’ve ever seen… Oh well.