Settings are reset every time I start Dota 2

[deLumren]

Yesterday I started having an extremely annoying problem in Dota 2, which never occured to me in over 3k+ hours of my playtime. My game settings are reset on each launch. It does not affect my Hotkeys, but stuff like Camera speed, Camera centering on Respawn, Unified orders via CTRL and such are all being changed to default, even the ones that I haven't changed since Reborn Update last August.
I also get "Your first Conduct Summary" every time I log in and get connected to regional chat room (which I disabled a long time ago).
This might be somehow connected to the video editing software that I installed yesterday, since it is the only thing I did on my PC besides browsing and playing Dota. However, I have completely uninstalled it from the system in hopes it would help and nothing changed.

What I tried so far:
- Reinstalling dota,
- cleaning launch options from Dota in Game Library.
- deleting steam user data from respectable folder.
- disabling/enabling steam cloud sync,
- deleting config.cfg and video.txt files from cfg dota folder,
- scanning for viruses and restarting pc,
- checking Dota cache integrity.

This seems to be issue with me only and noone in community has it. Please suggest solutions, because the only way I see is reinstalling my OS and I don't want to do that.
This is the most annoying thing I had in 9 years of Dota.

This is a copy of my Steam Support Ticket,
Maybe I will get more/faster help here.

[deLumren]

Still looking for help. Today I reinstalled steam, leaving steamapps folder intact, but nothing changed. It even got worse until I confirmed clould-saved options.
This brought my hotkey back to normal but all other options are defaulted and I get "first" conduct summary report on the log in.