I'm playing in the stoneblock modpack and wanted to create a "sky" room that makes it look like you are in a skyblock map rather than a stoneblock one. When I first placed down the inverted skyblocks, I saw the sun, moon and stars just fine. Several hundred placed skyblocks later, I am seeing only black during the nights and the transition gradients and daytime sky (and sun). None of the night textures are visible anymore. (No stars and no moon.)

Any idea on how to fix it? Is it possible? I'm not having any FPS lag with the setup, although I have placed about 400-500 skyblocks so far. (It is quite a large room.) I figure I have about another 100 or so to go before it's finished completely.

Was that change gradual or sudden? Have you done anything between first and last block? Does that depend in height?

Skyblocks take copy of screen just after sky is rendered, so what you see is what it would look like if you were in void. There should be no difference between having 1 and 1000 blocks, since picture of sky is taken once per rendering tick, so my first guess is that night sky might have been affected by some other mod.

Well, that's good that it doesn't matter how many are there as when I took them down, I had actually placed about 900. :D I think that Minecraft ran out of memory. I didn't realize that I had a bunch of other stuff open at the time. I relaunched the pack after closing all the extra programs, and all the textures are back. After I finish excavating the room and replacing all the sky blocks, I'll let you know how it turns out and if I run into any more issues with the rendering. I have a strong suspicion that I will be in the neighborhood of about 1500 sky blocks when done.

I had the same issue again after placing about 1500 or so. I added more memory to the pack and relaunched, and it seemed fine after that. I didn't lose sky textures again. I estimate that I placed about 2500-3000 of the blocks all told. When I am in my base looking at the area that contains all of the sky blocks, my fps goes from 50fps down to about 12-15fps. Inside the room where I only have about 1/2 of the blocks in my field of view, my fps is in the 30 range. Even though the effect is really cool, I don't think I will be able to keep them.