A light, off center striker hit is a round that wasn't fully chambered and locked into battery. Could be any number of reasons, including a dirty chamber, expanded case mouth (not crimped properly), oversize bullet, extended bullet bearing surface, or a bullet ogive that starts too slowly forward of the case mouth. This is very rare with almost any round in the OEM Glock barrel, but isn't uncommon with some aftermarket barrels.
With the barrel removed from your pistol, drop the rounds into the chamber. They should fall all the way into the chamber, flush or slightly recessed below the hood, and rotate freely. If not, you need to find out where they are interfering. I color the case mouth (about 1/4" back) and bullet with a marker and force them in by hand. The ink will be wiped from the area of the interference.
The rounds in your pic were not in the chamber like that. They are rotated from their firing position. If you marked them before chambering, it's likely, and common, they rotated while chambering. They won't normally stay in the same orientation going from the mag to the chamber, for a couple reasons. The primer strikes should be either centered like the "fired" round, or high-center. The rectangular dent on the primer of the fired round should be vertical, and can't be any other way. A round going into or out of the chamber can only be presented to the vertical center line of the striker, as the breach is a channel, the round slides up while moving forward into the barrel chamber, and any friction at the case head or rim can cause rotation. It is pulled straight out by the extractor with no rotation.
Life is tough. It's tougher if you're stupid. -- The Duke