I was just being lazy because I was in the middle of something. 
The actual messages sent to the printer are in the debug_network.log, at least in lan only mode.
Look for lines that include:
print_job: upload_3mf(withgcode)
print_job: json = {“print”:{
When I did it manually I did not send the upload_3mf command. The second line is the command that actually starts the print and has the name of the 3mf file, and the name of the gcode file inside it that tells the printer what to print.