How to assign blocks to particular regions on theme install in Drupal 8?

I’m creating a new custom theme for Drupal8, based on classy theme
I have 4 regions in MY_THEME

regions:
       header: 'Header'
       content: 'Content'
       footer: 'Footer'
       hidden_block: 'Hidden Blocks'

I don’t need some blocks, such as Search, Powered by Drupal, Footer menu, User account menu and etc. I use region ‘Hidden blocks’ to place unused blocks into it. I saw this method in drupal8_zymphonies_theme.

I found topic:
http://drupal.stackexchange.com/questions/193386/how-to-assign-blocks-to…
there is answer for my question.

So my steps next:
1. I install MY_THEME
2. Place block in regions
3. Export config files and remove from it uuid and core config hash
for example breadcrumb block block.block.MY_THEME_breadcrumbs.yml file

langcode: en
status: true
dependencies:
  module:
    - system
  theme:
    - one_page_site_theme
id: one_page_site_theme_breadcrumbs
theme: one_page_site_theme
region: hidden_block
weight: 2
provider: null
plugin: system_breadcrumb_block
settings:
  id: system_breadcrumb_block
  label: Breadcrumbs
  provider: system
  label_display: '0'
visibility: {  }

4. Place config files to MY_THEME/config/install directory
5. Uninstall my theme and clear all cache
6. Install theme

Then I go to block layout and saw that configs don’t apply and all blocks placed in header and content regions. And hidden_block region does not contain any blocks.

How to resolve my issue? Thx for help.

Drupal version: 


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