Texture UVs Shift with Camera Movement (ortho)

I'm trying to make a top-down sprite-based game, sort of like classic Zelda or Pokemon. Right now I am working on the tool that paints terrains so I can make area maps. I have a different file for each terrain, but each file contains tiles for about 120 different angles.

When the Quad for the terrain is created, it has the whole texture file as a texture. It then looks at neighbors that have the same texture and decides which UV coordinates to use. The code for this is super long (thousands of lines), so I don't think I'll be posting it.

I've got all this working fine. My problem comes in when I move the camera. As you can see in these two screen-shots, a weird line in the texture appears at one angle but disappears at another. All I have to do is move the camera. This also happens when I change zoom levels (by adjusting the orthogonal width).

Glitch Picture: Notice the brown lines in the grass, and the green lines on the right side of the grass?

Glitch Picture: Notice how the lines are now gone?

I have tried introducing blank lines to the Texture file between the Tiles and updated the UV coordinates. The problem persisted but with clear/see-through lines instead of solid colored lines as shown. The camera is in orthographic mode, so it isn't a perspective issue. It changes with angle, so it isn't a UV coordinate issue.

I would like to avoid having to make each UV coordinate it's own texture file if at all possible.

Thanks in advance.