Glad that helped! 😊
I'm not sure if it's a bug either, but I tried to reproduce it.
From what I can tell, it seems to happen when the wave direction is set to 0° and the scroll direction is left or right. Since the wave is also moving horizontally at 0°, the two motions may combine and make it look like it's drifting.
Could you show me your settings so I can try to match your setup?
Here are the combinations I tested:
0° wave + scroll right
0° wave + scroll up
90° wave + scroll right
That should help me figure out whether it's expected behavior or an actual bug.