APFS not working (?)

https://cdn.discordapp.com/attachments/311940388565024769/401818674022842369/unknown.png
I got i5-6600 with MSI ProVDH B150M mobo, also what is odd - my HDD secondary drive is converted by default to APFS, my main SSD which is Samsung Evo 850 is not and I get this error whatever I do. HS 10.13.4