My first thought, before I saw the pictures, was that the lawn got too much water from the rains we had up into early July. I believe the pictures tell the same story, but they add another plot. The fact that the initial sod pieces have not knit together tells me you got sold the wrong turf for your shade situation. There are shade tolerant varieties of zoysia but Zeon is not well known for being one of them.

Here is a picture of Shadow Turf, a variety of zoysia developed in Abernathy, TX (near Lubbock).

It is growing under the shade of a dense, English walnut tree. The only sunlight it gets is what you see. The turf was plugged a year earlier with 1-inch plugs on 12-inch centers. You can see some areas where the plugs have not quite grown together just north of the tree, but still, they have grown from 1 square inch to 10 square inches.

Unfortunately Shadow Turf is no longer being grown or sold. I've seen many a zoysia lawn converted to St Augustine once the owner sees what you're seeing. There is a decent chance that your zoysia is dormant from being overwatered. I've experienced it myself. If you stick it out, the grass will come back fine next April, but until then, it will look like what you have...or get worse. If we get prolonged rains next year, the problem will recur.

Is your lawn company in charge of watering? Because watering for 4 days straight is a big mistake for any lawn in any condition. I'm not saying you should not let them go (core aeration on a new lawn was a mistake in my book), but understand why you are letting them go. If you hire another company and continue to overwater, you will go through a lot of lawn companies.

that is a beautiful lawn.

Zeon was recommended to us due to it's shade tolerance. If that's not the case, I feel even more bad.

I've given up at this point. The new Lawn treatment guys came and said they are dormant and will grow back next year but they don't know what caused it.

I'm back to a once a week watering schedule. I did see some improvements but only when I grew it out to 3-4 inches. I recently cut it back down to 2inches as the lawn care company suggested and you can see the brown spots again.

At this point, i've gave up and will just wait til next year.

I tried growing a bit of the Shadow Turf pictured above. My situation changed right as I installed it. We had a storm that broke a limb off the tree which was shading the area where I put the Shadow Turf plugs. The grass still did fine; however, it was not without issues. Part of my experiment was to see if the zoysia would overtake the adjacent bermuda or vice versa. Turns out the bermuda was dominant. In addition there were times when we got a lot of rain, and the zoysia went dormant. It remained dormant no matter what I did for the rest of the season. The following April it looked great again.

Here is another picture of a neighbor's zoysia lawn. This seems to happen in the same spot every time we get prolonged rain.

You can tell by the landscaping the guy throws a lot of money at his yard, but he cannot fix this spot. Even if it happens in the spring, it remains like that throughout the rest of the growing season until the following April when it looks great again.

your zoysia looks like it has grubs, or large patch fungus. Have you treated for insects? should be done in May/June. also in the spring and fall you should treat with a fungicide. Headway G is a great product. You can purchase online. if you use a shovel to lift a section of grass, and see if you have grubs, or insects. Also arerate your lawn in spring, and fall. Lastly, have you watched the sprinklers run? Is there a head broken, or inadequate coverage?