PiMarquee2 Framebuffer Issue?

[drewmillr]

I'm having trouble with my secondary display on a Raspberry Pi 4B. The monitor seems to be working fine, but all my marquee images have a large black border around them and do not fill the screen.

Here are the details of my build:
PI Model: PI 4B+ 8GB
Power Supply: CanaKit case and power supply (from Amazon)
RetroPie Version: 4.8
Built From: Pre-made SD Image on RetroPie website
USB Devices connected: 2 DragonRise keyboard input devices for arcade buttons, 1 USB trackball
Guide used: Followed steps from https://github.com/losernator/PieMarquee2
Emulator: MAME

The second monitor is plugged into the micro-hdmi port farthest away from the power supply.

When the system first boots up, I get a full height image of the rainbow screen on the second monitor:

When emulation station loads and I choose a game, there is a large black border around all the marquee images:

I've tried changing the settings in /opt/retropie/configs/all/autostart.sh file using the information I found here:
https://retropie.org.uk/forum/topic/25780/pi-4-dynamic-marquee-using-secondary-hdmi-output/16

#fbset -fb /dev/fb0 -g 1920 1080 1920 1080 16
#isdual=tvservice -l | grep "2 attached device" | wc -l
#if [[ $isdual == "1" ]]; then
#/usr/bin/python /home/pi/PieMarquee2/PieMarquee2/PieMarquee2.py &
#fi

/usr/bin/python /opt/retropie/configs/all/PieMarquee2/PieMarquee2.py > /dev/null 2>&1 &
emulationstation  #auto

That didn't change anything, so I commented out the code that I added. I also tried adding the settings that @losernator recommended on his GitHub page:

If you use different display as second monitor, You may need to change framebuffer resolution.
Add this line to /opt/retropie/configs/all/autostart.sh
fbset -fb /dev/fb0 -g 1280 720 1280 720 16

Oddly enough, I re-imaged my PI to make sure it wasn't a monitor issue. I loaded Raspberry Pi OS with desktop, and everything was automatically recognized and configured correctly:

Here's the output of tvservice -l if it helps:

pi@retropie:~ $ tvservice -l
2 attached device(s), display ID's are : 
Display Number 2, type HDMI 0
Display Number 7, type HDMI 1

If I look in dev/ I only see one device fb0. I thought there would be an entry for fb1?

My apologies for the long post, but wanted to provide as much information as possible.

Thank you for any input!