Textures not working properly on OS X

Hello,

I have been using UE4 for some time now with my pc, but I got a MacBook and I wanted to try it out there. My problem is that everytime I apply a texture or a new material to an object it goes into this checkerboard pattern as if there isn’t a texture file. The texture editor as well doesn’t show anything other than black on the texture preview.

Not sure how to get this working, if I save them and load them on my PC all the textures work fine even if applied on the Mac.

Thanks in advance.