Waist bone won't move. Only rotates in place The bone I used to control my character's upper body is stuck in place and only rotates when I try to move it.

From what I checked, it is not the same problem as this question:
In Pose mode, my bones are stuck in rotate, and wont transform

Yes, clearing the parenting to the root bone solves it, but that is not what I want and from all the models I've done before, this is the first it happened.
Here is the model:
https://drive.google.com/open?id=0B4Okp_8X219XU0s2Zk1Nb280SkE

Any ideas?
Its is related,  actually, since your Main bone is acting like the last bone in a connected chain

Enter Edit Mode, select the Belly bone and go to its Bone Data Panel to uncheck Connected. Do the same for the Hips bone. Now you can translate the Main bone in Pose Mode