Okay great, I got it figured out for me as well, tested it on three of the systems it was failing on before and it's working for all. I have to do it exactly like this or it doesn't work, which oddly...

Ah I see. Yes I got around it by clean installing 1709 and installing Office before allowing updates to carry it up to 1803, but stupidly formatted my USB installer and now I'm stuck with the 1803...

I've been having the same issue on my end with any machine running 1803 regardless of clean or dirty install. If it's running 1803 and you try install ANY version of Office it fails with the same...