CSS defined in library is not included, but theme works themes/custom/teleci/teleci.info.yml:

base theme: bartik
core: 8.x
name: Teleci
package: Custom
type: theme
version: "1.1"
libraries:
  - teleci/global-styling


themes/custom/teleci/teleci.libraries.yml:

global-styling:
  version: "1.1"
  css:
    theme:
      css/override.css: {}
      css/style.css: {}


I also have custom template in themes\custom\teleci\templates\block--teleci-branding.html.twig that is loading correctly - that means the theme works. But the CSS files are not included (they are not in the generated HTML). 

I tried


php drupal.phar cr all
setting bartik as default and then set my theme back
clear browser cache
open in private window
disable JS/CSS minification in settings
check both yml files in yamllint.com
disable base theme (bartik)


I'm out of ideas and would appreciate any help :(

Update: I created minimal theme (that does not work as well) for you to test. Could you please test it and let me know if it works for you? https://github.com/tomasfejfar/drupal-simple-theme/ (i have it in /themes/custom)

Update 2: the mini-theme works when I fixed a small bug that is not present in my theme. So there is something about my theme that makes it break.
Finally it seems to have been fixed. I re-created the same template again under a new name. Checked the diff of theme.info.yml and theme.libraries.yml files - only difference is the name. The new template has all the same functionality the previous had and is 1-to-1 copy except for the name. So only thing I can think of is that while playing with the template something has broken and left some residue in the database that prevented the theme from functioning properly ever again.

Thanks everyone who tried to help!