试了下初始工程，显示图标没有问题。
请你检查下MV引擎的安装目录，里面的  ICON 图片是否存在问题。

# 如果图标图片没问题,那么可能  this.drawIcon 的原对象被修改了.
    可以试试添加以下代码.
方法1:

JAVASCRIPT 代码复制

Window_Custom.prototype.drawIcon = function(iconIndex, x, y) {
    var bitmap = ImageManager.loadSystem('IconSet');
    var pw = Window_Base._iconWidth;
    var ph = Window_Base._iconHeight;
    var sx = iconIndex % 16 * pw;
    var sy = Math.floor(iconIndex / 16) * ph;
    this.contents.blt(bitmap, sx, sy, pw, ph, x, y);
};

Window_Custom.prototype.drawIcon = function(iconIndex, x, y) {


    var bitmap = ImageManager.loadSystem('IconSet');


    var pw = Window_Base._iconWidth;


    var ph = Window_Base._iconHeight;


    var sx = iconIndex % 16 * pw;


    var sy = Math.floor(iconIndex / 16) * ph;


    this.contents.blt(bitmap, sx, sy, pw, ph, x, y);


};

方法2:

JAVASCRIPT 代码复制

Window_Custom.prototype.drawIcon = function(iconIndex, x, y) {
    var bitmap = ImageManager.loadSystem('IconSet');
    var pw = Window_Base._iconWidth;
    var ph = Window_Base._iconHeight;
    var sx = iconIndex % 16 * pw;
    var sy = Math.floor(iconIndex / 16) * ph;
    bitmap.addLoadListener(function(){ this.contents.blt(bitmap, sx, sy, pw, ph, x, y);}.bind(this));
};

Window_Custom.prototype.drawIcon = function(iconIndex, x, y) {


    var bitmap = ImageManager.loadSystem('IconSet');


    var pw = Window_Base._iconWidth;


    var ph = Window_Base._iconHeight;


    var sx = iconIndex % 16 * pw;


    var sy = Math.floor(iconIndex / 16) * ph;


    bitmap.addLoadListener(function(){ this.contents.blt(bitmap, sx, sy, pw, ph, x, y);}.bind(this));


};