Fontconfig weight configuration not taking effect

I have the following fontconfig configuration, but the font weights aren't changing as expected. I discovered that changing target="font" to target="pattern" makes it work.

Noto Sans
    
    
      medium
    
    
      medium
    
  

  
    
      PingFang SC 
    
    
        medium
    
      
        medium
    
  

  
    
      SF Pro Text
    
    
        medium
    
    
      medium

Based on my research, I believe target="font" should work as well. Could anyone help me understand what might be causing this behavior?