I have 3700-itx with default UEFI settings in BIOS(V1.30). I just change the settings about Fan control and VGA, so I don't think it matters.
I use a USB 3.0 memory stick and the latest iso file to create a bootable device. When I plug it into USB3.0 port, I met the same problem just like you. BUT when I plug it into USB2.0 port besides ps/2 port, it boots properly.
By the way, I use UltraISO to create the bootable device, but I have tested to use Win32 Disk Imager and img file to create a bootable device, it seems OK. Also I have change the VID & PID in syslinux.cfg.
I don't know if it matters, but I hope this can helps you. Try to use another usb stick and create the bootloader in a different way.