I redone the sky in my 2D game for a smoother gradient and I also better optimized it. However, I'm getting this strange black area on the far right:





The texture is 1x256. I set the panel's scale_x value to 1024 to stretch it all the way across the screen (the scale_y value is not used). Oddly enough, slightly less (by 10 pixels) than half the screen has the black area. I tried widening it to 2x256 and using scale_x at 512 and this causes the rightmost 1/4 of the screen to have that black area. The screenshots show the 2x256 version. My previous sky used a 16x256 texture scaled to 64 and it didn't have this problem at all. Why is it doing this and how can I fix it without using a 16x256 texture or using 6.40.4 (as 6.40.4 doesn't have this)?

I'm using 6.31 Commercial (my 2D game doesn't work right (short of adding another 2000+ lines of code) on 6.4x).

Edit: added note about this and 6.40.4