The shells being bunched up shouldn't be an issue. The trick is getting that first shell out of that bunch. When you pull the shells out of the caddy focus on pinching the 4th shell with your thumb and index finger and slip your driving finger in between the 4th and 3rd she'll to separate that first one.
Once you load the first one. Keep your thumb inside the loading port and in contact or very close to the lifter. As you slide the thumb back along the lifter rotate your wrist around to the right and down so that the next shell comes under the loading port.