NameError for importing random and numpy.random, but nothing else

I've run into a strange case in my Python code, and I'm trying to figure out why this occurs.

from numpy.random import uniform
for r in range(1, rounds):
    sample = {item: uniform() < probability for item in items}

When I run the above code, I get the following NameError:

File "sample.py", line 6, in <module>
  sample = {item: uniform() < probability for item in items}
File "sample.py", line 6, in <dictcomp>
  sample = {item: uniform() < probability for item in items}
NameError: name 'uniform' is not defined

This is very strange, since I am importing uniform directly before using it in the following line. I got the same error using the random module. I'm using other packages in my code (including argparse and pickle) but only the random number generation is giving me errors. I'm running Python 3 on a Windows machine. I also get the same error when I move the import statement inside the for loop.

for r in range(1, rounds):
    from numpy.random import uniform
    sample = {item: uniform() < probability for item in items}

What could be causing this error?