I see where you went different from me. I don't run Windows. I used the Linux Version of Unetbootin. And Yep. I have used Unetbootin a bunch. So Pendrive is Always formatted as Fat 32.unetbootin-windows-408.exe to put antiX-M8.5-rc2.iso on my Flash Drive
If your method using Windows Unetbootin works on 1.1 USB with Plop Boot Manager (which I am assuming you made the floppy in Windows)
Please Let me know. Also if you have any links or notes for making the PLOP Boot Manager Floppy Disk using Windows so I can include a Windows way of doing it in the Wiki. Appreciate any feedback.