figured it out, and it's ridiculous!
I started building a new board with sockets for everything, and was studying the schematic and realized that I had soldered all of the LED's backwards; which I confirmed by applying a power source to an LED and observing they were lighting up the wrong way.
The confusing part about it was that it actually worked for a while prior to just staying full bright so I had assumed it was all wired correctly.
Thank you all for the tip to add the noise reduction resistors.
I do have two decoupling capacitors on the 7219.
Aside from that, are there other design tips you would recommend in working with the 7219?
Does it matter which digital pins you use as inputs to the 7219 if I'm using the ledcontrol.h library? I ask because I'm not using the commonly used 11, 12, 13 SPI pins, which may be ok since I'm not using the SPI.h library. I'm considering switching back on future versions.
New board is working good on the pro-mini.
Thank you to all for your help,
Robert