1.12.2 button sounds issue

[denchInside]

I've got a custom main menu configuration that works on 1.7.10. In 1.12 everything works as it should except button sounds. After adding "hoverSound" and "pressSound" parameters the button has no sounds at all. It isn't resource loader fault because it replaces other sounds. Here is my mod configuration:

1. custom main menu (Example of a button)

"singleplayer":
      {
          "hoverSound" : "mainmenu:hover",
          "pressSound" : "mainmenu:click",    
          "text" : "Играть локально",
	"normalTextColor" : 12303291,
	"hoverTextColor" : 3125670,
	"texture" : "mainmenu:textures/btn.png",
          "posX" : 100,
          "posY" : -20,
          "width" : 153,
          "height" : 20,
	"imageWidth" : 100,
	"imageHeight" : 50,
	"alignment" : "left_center",
          "action" : 
          {
              "type" : "openGui",
              "gui" : "singleplayer"
          }
      }

2. resource loader