Thanks for the responses everyone!
@bko, I had tried DAC prior to posting, but got the same result. However, once I adjusted my range to 0-255 and moved to pin A5 based on @justinmy’s recommendation , analogWrite started to work again.
Now I’m just curious why it didn’t work on A6 or A3. Either way, I can stick to A4, A5, and A7 for the moment. Thanks for the help!
There is a difference between PWM signals which are quickly switching between HIGH and LOW, always fully opening the diode, while DAC pins do in fact output analog voltages between ~0V and ~3.3V.
If your output voltage is below the diode’s typical forward voltage (depending on color of your LED), it will still stay shut and not emit any light, but once the forward voltage is exceeded, the diode opens and the LED will come on fully, since the brightness is not voltage but current controled and an DAC will still drive the same current independent of the set voltage.
I was about to say the same thing as ScruffR, but he beat me to it 
you can always jumper a pin with PWM capability to D7, to hijack the onboard led.