Placed Carpets despawning on a Nether Highway

I have made a 4000 block nether highway and i was going back to base on it and i realised as i was coming back that a heap of carpet on one side of the highway i placed down had just disappeared for about 318 blocks. i decided to break underneath the floor to find a cause only to find no fire or anything, the only thing i found was a few lines of spruce wood i used to cover some holes. I added some extra photos to show what the ends look like it goes from -1661, 119. 2 to the end being -1997, 119, 2. As shown in the photos you go eye level with the carpet.