[1.11] Why is my gui texture randomly being replaced by the alphabet...?

This is the weirdest problem I've ever had  when modding.

I'm trying to make a gui that renders text over a texture in the corner of the screen.

There are four parts of the texture that I'm rendering separately, since if the player doesn't have something I don't want that part to render.

It all works perfectly, except the third and fourth parts SOMEHOW are losing my texture and instead it's rendering what looks like the default Minecraft font texture at more than double resolution?

Pictures:

And this is the code:

	@SubscribeEvent
	public void onRenderGui(RenderGameOverlayEvent.Post event)
	{
		if (event.getType() != ElementType.EXPERIENCE)
		{
			return;
		}
		IEchoesCapability echoes = mc.thePlayer.getCapability(EchoesManager.ECHOES, null);

		if (echoes == null)
		{
			return;
		}

		this.mc.getTextureManager().bindTexture(hud);

		int y = 0;
		int y1 = 4;

		if (echoes.getEchoes() > 0) // The rune-like symbol. Works.
		{
			this.drawTexturedModalRect(1, y, 0, 0, 136, 29);
			drawString(mc.fontRendererObj, TextFormatting.WHITE + "" + echoes.getEchoes(), 16, y1, colour);

			y += 30;
			y1 += 15;
		}
		if (echoes.getInsight() > 0) // The eye symbol. Works.
		{
			this.drawTexturedModalRect(1, y, 0, 29, 136, 29);
			drawString(mc.fontRendererObj, TextFormatting.WHITE + "" + echoes.getInsight(), 16, y1, colour);

			y += 30;
			y1 += 15;
		}

		int bullets = 0;

		for (ItemStack stack : mc.thePlayer.inventory.mainInventory)
		{
			if (stack.getItem() == Registry.quickSilverBullet)
			{
				bullets += stack.func_190916_E();
			}
		}

		if (bullets > 0) // The bullet symbol. Does NOT work, renders alphabet instead.
		{
			this.drawTexturedModalRect(1, y, 0, 58, 91, 29);
			// TODO draw amount

			y += 30;
			y1 += 15;
		}

		if (echoes.getCords() > 0) // The spiral-like symbol. Does NOT work, renders alphabet instead.
		{
			this.drawTexturedModalRect(1, y, 0, 87, 91, 29);
			if (echoes.getCords() >= 3)
			{
				// TODO alternate cords icon
			}
			// TODO draw amount

			y += 30;
			y1 += 15;
		}

		if (echoes.hasAsh())
		{
			// TODO alternate bullet icon
		}
	}

How on earth does this happen and how do I fix it?

And for the record, I tried adding:

		this.mc.getTextureManager().bindTexture(hud);

pretty much anywhere before it starts displaying the alphabet to try to fix it, but the result is that what ever drawTexturedModalRect() came next just doesn't get called at all.