LayOut export to PDF, text strokes transparent when overlapped

I found when exporting LayOut drawing to a PDF file, the text in font of Source Han Sans are not rendered correctly. Some areas where strokes overlap with each other become transparent. It seems to me the only problematic fonts are Source Han Sans and Source Han Serif. I’ve seen this kind of problem in other software when the path of the vector shape of two overlapping strokes are opposite, you can fix it by manually reverse one of the paths. But is it possible to fix it in LayOut?

There are some fonts that aren’t supported by Adobe Acrobat. I haven’t seen this particular font but it may be one of those fonts. a search for ‘Source Han Sans problems’ turns up a number of hits.