Having trouble with Marlin's manual mesh bed leveling. Anyone able to shed some light on it?

I configured manual mesh bed leveling and the LCD bed level option in firmware so I can do everything with the help of a guide via LCD. After flashing the firmware, I was able to go to Prepare > Bed Leveling > Bed Level and setup proper measurements for my mesh. If I run G29 the printer spits back a nice 5x5 mesh. Great!

However, it shows the status as "off" and I can't figure out how to turn it on. Once in awhile the option will show up in the LCD, but even if I enable mesh leveling via the LCD it disables itself at the beginning of each print. I can tell that it's not working because of G29's output and because the steppers are not compensating during prints. How can I get ABL to stay on? Is there a new command I need to add to my GCODE for manual ABL as compared to auto ABL? Normally I just run G28, G29, and print.

Note: For those familiar with MakerFarm, I'm using the same functionality in Marlin they use for the Pegasus line. They refer to the process as "firmware bed leveling."