Thanks Steve.
Finally got it to work after many tries. Your response was the key.
What I found out was that not only inside the actual TG3 file does the Render Node's Output path need to be a network drive, but even the batch command line needs to have a network drive.
For example, my problem stemmed from the fact that all my slave machines have a D:\_temp3ds folder where I save each machine's output locally. Later I move and consolidate everything. Yet doing this (using D:\ like your T:\) had TG3 saving each file as a .bmp only. However, changing only the .tgd's Render Node Output Path to a network drive did not solve the problem. Each slave machine still dumped each rendered frame, without any rendered elements, as a bmp only, into the folder in TG3's\Preferences\File Saving\Sequenced Output location.
So the batch command also must have the location of the .tgd file as a network drive. I still wanted to use the D:\ drive on my main machine, so I went through the network and called it "\\Flynn01\D-Bern\filelocation".
FYI to anyone else, the "-x" variable noted on the first page of this post does not seem to be needed anymore.
cmdjob -jobname:"Backburner-job-nickname" -manager:10.0.0.2 -priority:50 -taskList:"D:\_tempTG3\gathered_files\thisisthetasklist.txt" -taskName:2 "C:\Program Files\Planetside Software\Terragen 3\tgdcli.exe" "\\FLYNN01\D-Bern\_tempTG3\gathered_files\defaultTG3-networksave.tgd" -hide -exit -r -f %%tp1
Also, for anyone reading this at a later date:
I was trying NOT to hard-set the TERRAGEN_PATH environmental variable in case I used TG2.5 again, per the recommendation in TG3 Doc's file. However, I ended up hard setting it on all the nodes anyways, so I cannot say if it did help in the end or not. For anyone who wants a quick way of setting it for all their render nodes, simply copy the attached "TG3 environ...txt" file, change the extension to .bat, and run it on each machine. Takes two seconds.
Other notes:
The Backburner help file says that the -manager:IP.IP.IP.IP address is not needed and it can use the default port, but I found the TG3 file loads into Backburner faster if you do include this tag.
You can set the -priority:50 or whatever you want, Critical, 01, etc.
In TG3's Docs\win_command_line.txt file, it notes how you can set up specific frames within a batch command (non-Backburner), but Backburner does not pay attention to that notation. To do so in Backburner, use a Tasklist. One is attached for starters. Use the Excel to quickly copy and fill the frames you want, even odd or spaced frames. Then copy all the data from those two columns into a txt file. This way the job in Backburner will show up with the same frame # as the actual frame you are rendering. Without the tasklist, you may be rendering frames 14-17, but it will be listed in Backburner as tasks #1-4. That makes it hard to track if a specific frame is having a problem. The tasklist can be locally referenced in the .bat file.
The tasklist attached is the equivalent to specifying: -f 1-3,26-41/5,90-93.
Cheers,
Matt