I got an error when exporting a line graph with filled areas. The filled areas I made by using all lines in the graph (fill to next data plot) appear boundary at the bottom when export PDF files. But it's not seen in the graph in Origin and also in image files.
Would you tell me which version of Origin you are using?
Just as we known, a similar problem happens in Origin 2017 and 2018, but has already fixed since Origin 2019, ORG-15466 "P13-2". Sorry, there is not a workaround for this problem.
Maybe you can send us the project file to let us confirm it, via tech@originlab.com.