I created a bootable USB stick with Startup Disk Creator in Lubuntu 16.04. Here are some screenshots:
The problem is that created USB stick is not seen during PC boot - just like there is not any flash drive inserted. Disabling UEFI security boot doesn't help. There is no such a problem when I create bootable USB stick with Universal USB Installer 184.108.40.206 in Windows. Does it look like a bug in Startup Disk Creator, or am I just doing something wrong?