No tie between objects

[strelok00]

Hi I've just installed NetBox (3.1.6) using docker image and I am trying to do next initial steps:

Created Site (DC-1)
Created Region (MSK)
Created Site Group (DC-MSK)

After that I tried to make tie between Site and Region/Site Group.
I edited Site and trying to choose Region (MSK) in drop down menu - but list of regions is empty.
The same situation with Site group (DC-MSK) - empty list in drop down menu for Group.

So, what's wrong ?