How to troubleshoot max7219?

I guess it just means you didn't show enough on the schematic with names called out to tell what's actually supposed to be connected.
I think it's easier to follow by showing a signal name on everything and skip the bus drawing altogether.

It appears the way to read the netlist is:

Net Part Pad Pin Sheet

Net/Signal name: MATRIX1
connects from device name: 16
external pin #: 8
internal pin name: 8

connected to:
device name: IC1
external pin#: 2
internal pin name: DIG0

So breaking it up like that, the netlist makes more sense.

Okay, so given that things appear wired correctly:
What value is Rset?
Is Vcc at 5V?
Is the matrix installed upside down?