For some reason whenever I try to edit the sandstone texture, it applies it to the top block but none of the bottom, I've attached an image of what it looks like and what I've edited my sandstone textures to be in the terrain.png.
Can someone please tell me what I'm doing wrong?
Thank you for the prompt and informative response.
This fixed it, but if you have any time could you explain to me a little bit about what CTM is and why I was having that problem?
CTM means Connected Textures Mod. It allows for blocks to be textures based on how they are "connected" to other blocks, have random textures, use a pattern over a large area, and have more different textures per block (like a top face different than the side faces, or side faces different from each other).
You had this issue because of how Optifine implements CTM. It loads it from the default ctm.png even when a texture pack is used, resulting in "defaulted" CTM textures.
As soon as you add extended CTM for any block that uses the classic CTM sheet (glass, bookshelves, sandstone), Optifine will stop trying to use the default ctm.png for anything except glass panes. You can fake that out, too by making all of the glass tiles on ctm.png have the same texture as non-connected glass.
Thank you, both of you. I did not understand this before. By the sounds of it, this CTM is probably heavily related to another issue that I am having with the grass at the moment. I'll post a screenshot.
As you can see, there is a light green "belt" around the block, where it should be the same colour as the rest of the grass (which in the terrain.png, it is gray, all the same colour.) "BetterGrass" is also not working when it comes to placing grass blocks on top of each other, also.
Do you have any suggestions or ideas of what may be causing this and how I can resolve the issue?