Please try the following:
Make sure you have the hard drive in the priority boot in the BIOS as the primary hard drive.
Then, if you have any other devices connected to the unit, for example, a flash drive, that can delay the boot process.
Also, if you access the BIOS, in the devices tab, select SATA and then in the hard disk pre-delay option, you can set it up to 0 and that can make the system to boot faster.
priority boot is checked - no oddities / all fine
sata enabled / ssd recognized / delay = 0
still i am watching the intel nuc logo for more then 20 seconds *puzzled*
* edit - there is a new bios update # Intel® Download Center version 0040
with version 0031 bios boot time = 30 sec [ windows task manager ]
with version 0040 bios boot time = 10 sec ... that is an improvement !
* do i need legacy boot support on this machine ?
Legacy boot can help improve compatibility with older operating systems that weren’t designed with UEFI in mind. Is up to you if you want to have it enable or not. In my case I prefer to have it enabled.