• In the level summary, the circular 'fast time' icon does not light up, while the other two light up correctly.
  
• Achievements are not recorded despite fast times.
  
• Resetting the game in options or does not help.
  
• Logging into Steam on another computer does not help.

After following the steps below, I was able to complete the game 100%.

• Click FrostRunner 'gear' icon on Steam launcher
  
• Click 'Properities'
  
• Turn off Steam Cloud
  
• Open 'C:\Users\YourName\AppData\Local\FrostRunner\Saved\SaveGames' folder (instead 'YourName' use your Windows user directory)
  
• Rename 'ThinkArcade.sav' to 'ThinkArcade.backup.sav'

Unfortunately, you have to complete all levels again. Fortunately, after a little practice, achieving fast times is not particularly difficult. You also need to get all the collectibles, you just need to touch them, you don't need to survive (without them you won't unlock insanity levels).

If you have any problems, there are excellent video guides here.

I will be grateful for any comments and comments, can you also tickle my ego with a community award?