Scatter: fill under line fails when Y offset is used

OffsetY = 0 | OffsetY = 3
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![image](https://github.com/user-attachments/assets/51844b8c-f5a3-401e-96a9-ed0765f52848)|![image](https://github.com/user-attachments/assets/14b8b0c9-a54e-46bf-8faa-e3a713c8e6a8)
