Bootcamp can't find O/S / Flashing question mark
I have installed a new OWC SSD and I have installed Mojave and i’d like to install windows via the bootcamp assistant. The bootcamp assistant asks for the iso, then asks if I’d like to make a second partition on my Mojave SSD, then it downloads all the files and reboots, I then get a black screen with a white Apple logo and then a flashing question mark/folder.
If I then power off and back on, it boots as normal into Mojave. Bootcamp offers the option to remove the windows partition. Disk util shows no sign of a windows partition.
If I hold option while booting, I just get the Mojave SSD which brings me back to Mojave.
Can anyone shed any light on this please? I’m fully updated to 10.14.6
Any help, much appreciated, cheers.