PC client bug: Matchmaking button turns grey / does nothing after recent patch (Mobile works fine)

Body:

Hey everyone, I’ve been running into a frustrating client bug after the latest patch and could use some help or see if anyone else is experiencing this.

• The Issue: The "Find Match" (or "Найти игру") button in the PC client becomes clickable, turns grey/darker when pressed, but nothing happens—queue simply doesn't pop or start. This happens in both TFT and regular League modes.
• What works: My account is totally fine. I can queue up and play without any issues on mobile.
• What I've already tried:
  • Restarted the Riot Client and killed lingering background processes via Task Manager.
  • Cleaned game cache / deleted Config and Logs folders.
  • Ran a full file repair through the Riot Client.
  • Flushed DNS (ipconfig /flushdns and netsh winsock reset) and restarted my PC.
  • Dealt with a secondary Vanguard error (VAN 216) by checking service startup and folder exclusions, which is now gone, but the matchmaking button still remains completely unresponsive.

Has anyone encountered this or found a fix? Any advice would be greatly appreciated!