If you want to change chapter, but you see only introduction and Moskov, turn off steam cloud sync through game properties in the Steam library, then choose "general" and make sure that the last option is disabled. At least that's how I fixed it. :) (This will help with corrupted save files too)

• Your hard drive might have some errors on it, try scanning it:
  - Right-click on the drive you want to scan (I suggest scanning all of your hard drivers) and select Properties.
  - In the "Tools" tab there should be an "error-checking" option, click on the "check" button.
  
• Simply right-click on Metro Exodus and launch it as Administrator;
  
• Update ALL of your computer component drivers. Why all of them? Just to make sure that you don't have any faulty component drivers installed c:

Good luck on your "Exodus"!
If you don't mind this, leave like or rate this guide so more people will be able to find out how to fix those errors :D