So I deleted and created the custom programmer again and paid attention to the NEXT button.

Code:
-TSBUR223673449 -P$target-device$ -F$hex-filename$ -E -M -Y -OL -OB
Nope, NEXT button never comes on, and the command line seems complete if I EDIT the programmer again.

Name: PICkit4 custom pgmer B.png Views: 12066 Size: 24.2 KB

I compile and program again, I see HEX FILE NOT FOUND blink, and the command line window keeps closing despite the new command line.

Via the PICKit3 programmer
-TSBUR171738083 -P$target-device$ -F$hex-filename$ -E -M -Y -OL -OB
or
-TPPK3 -P$target-device$ -F$hex-filename$ -E -M -Y -OL -OB

Command Line Options:
-E erase before programming
-M program entire memory
-Y verify after programming
-OL release from reset
-OB batch mode (leaves cmd line window open)
I'm starting to think the command lines for the PK4 are different...?