Questions About Saving Spot Colors for TIIF Files in Photo Paint for DTF Prints

We got a DTF (Direct to Film) printer and are trying to figure out how to use it to print full color shirt transfers. the instructions say to explicitly save TIFF files and to make a custom Spot Color Channel with a 1-2 pixel choke on it as a white base. It also explains that the spot color must be titled "W1" exactly as written. So I made a custom white spot color named W1 since you cant just name your spot color when doing that for some reason. 

I've tried this several times without the W1 spot color name and with it but I keep failing. I'm not even sure I'm making the spot color channel the correct way (It shows instructions with Photoshop). I start by selecting the image and contracting the selection by 1 pixel. Then I make a new black spot color so I can see what I'm doing. I then paint in the selection or erase the inverse selection (I've tried both ways) to make the desired white base shape. Then I change it to the "W1" custom Spot Color. 

In the program we have to use it continuously adds a gray background to the transparent image. Its transparent in every other program I open it in except the programs we need to use to actually print it. When I open the TIFF file in Photo Paint there are a couple strange things though. When I look at the channels a new mysterious channel appears which is not in the CPT file. The channel is called "(Alt+5) every time and appears to be the invers of "W1". Both Alt 5 and W1 are unchecked as well meaning they aren't visible. They both appear to be a 50% red color. It basically just looks like I have a mask selection, but I don't. I have a feeling this is what is making the gray background when I import it into the program because I guess it just sees/ shows all of the channels. 

Why is it doing this and is there a way to prevent this? Am I creating the spot color channels wrong? I'm going to download photoshop and see how that works for now