Problem installing Windows 10 1909 on new iMac

I tried to install Windows 10 version 1909 x64 on my new 27in. iMac using Boot Camp Assistant.

All goes well, e.g. selcting the iso and partioning the 1TB SSD hard drive. After loading Windows support software 7348, I get a this message, "The Finder is about to quit. Click continue to eject without burning "" to it. "" won't be deleted. You can burn it to a disc later." I click Continue and nothing happens... The Mac does not reboot and the Windows installer does not start. Anyone know why?