It seems that Ubiquity is having problems with USB drives, at least in our cases. I re-ran the installer with my USB drive unplugged, and was able to get to step 4. I'm not sure how this can be fixed.
You saved my life with this I was trying to figure this out for hours and all i had to do was remove my external usb hardrive n it went through the rest of the processes instantly. Thanks again. Just joined this site so not yet sure if yall +rep but if you do you def got +rep from me twice. Thanx.