I feel like an idiot. I DID find the issue. Super simple. I have never asked for forum help up to this point in my life, and I chose this issue. Such is life.
The problem was in the homing configuration. I was relying on the configurator too much. I did not consider that G28 was running the homeall script. I only updated the homez script. After hitting the end stop, it was setting Z0 in the homing scripts, so I fixed that in the G92 command.
I could have solved the issue with the end stop being at the low end by adding a subsequent command to lift the cutter in the homing files. Obviously. What a doofus.
I got that fixed, but then decided it would be really nice to have a prompt to manually zero the bit after it found the end stop, as my surface height may change a lot. I did the following in the script:
; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v2 on Sat Apr 06 2019 08:38:03 GMT-0600 (Mountain Daylight Time)
G91 ; relative positioning
G1 Z50 F6000 S2 ; lift Z relative to current position
G1 S1 X-645 Y-920 F1800 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 X5 Y5 F6000 ; go back a few mm
G1 S1 X-645 Y-920 F360 ; move slowly to X and Y axis endstops once more (second pass)
G1 S1 Z190 F1800 ; move Z up stopping at the endstop
G90 ; absolute positioning
G92 Z175 ; set Z to axis minimum (you may want to adjust this)
G91 ; relative positioning
G1 Z-50 F1800 ; move Z Down 50
M291 P"Set Manual Z Height" S2 X1 Y1 Z1
G92 Z0
G90
M292 P0
This all works wonderfully when manually selecting "Home All", but when G28 is called from a job, it gives me the prompt and does not allow me to manually move the axis while the job is waiting for the homing to complete. If I just click okay, the job is stuck in a paused state that requires me to reboot in order to regain control. If I could nail this part down, it would resolve any issues I am having heretofore.
One thought I have had is that maybe there is a command to set an offset in the same manner instead of setting Z0 manually.
Thanks again for your help!