Nessiesson

This is a separate issue that has nothing to do with creative mode or deleting items. This bug happens in survival mode as well and only affects statistics.

Based on 1.12.2 (with MCP 940, mcp-stable-39 mappings), code, the fix is very easily. In the class `BlockConcretePowder` (which extends BlockFalling`), there is an overridden method missing. Using 1.12 symbols, the method will something like

public class BlockConcretePowder extends BlockFalling {
// ...
    @Override
    public int getDustColor(IBlockState state)
    {
        return state.getValue(COLOR).getColorValue(); }
    }
// ...
}

Hopefully, this (simple) fix will help Mojang.

Why is it no longer valid for coordinates? There is plenty reason to keep it in the game.
EDIT: Keeping it in the game is logically consistent with ~-<number> since ~ specially means "the current coordinate", hence why +<number> explicitly states "the current coordinate PLUS <number>". Meanwhile, ~<number> is confusing because it is not what you expect: newcomers are much more likely to think that it means "current coordinate TIMES <number>" rather than "the current coordinate PLUS <number>".