Okay, I just reinstall the toolkit, again. Version 22.214.171.124 gave me that same error as before, but for some reason this time 126.96.36.199 worked when run as admin (which is what I'd been doing). I'd tried that same process three times without success.
Weird. At least it is working now, but I do wish I know why it hadn't worked up until now
Thank you guys for all the help. Hopefully I can get this custom ready for beta testing now.