When you place a limit order above the ask, I can

When you place a limit order above the ask, I can see getting a better price, in which case the volume of your order would not display correctly, (I also use Fidelity). But, when the order is placed at ask/bid and there is no one else currently closer to the spread for that MM, my orders have always displayed. That said, if someone adds to the volume it will go up, but I was just thinking it was weird for seemingly limitless volume to go off at the bid and the MM didn't falter. Usually, you see the MM ask/bid placement time at least change... no?