Because you're getting a Hopper Empty error, I don't think the issue is related to a setting. If it was a setting, the machine would not even call for the hopper and just go to hand pay. Since the machine fails the 1st step due to an error, it calls for an attendant.
Also, have you tried not doing split pay and JUST do a normal hopper pay, like all credits to hopper? If so, did the machine give the same error? By setting it up with normal hopper pay, you know that the settings are basic, and you can't mess it up. If it fails to do a normal pay, the machine might have a wiring issue to the hopper.
Have you tried 4.7.1 Hopper Test ?
The hopper may be good, but there may be an issue with the machines wiring to the hopper.
And 1 more thing, do the hoppers spin at start of cash out? Are you using the correct hopper wheels for your coin size? Just figured I cover everything I could think of.