Hi
I have a figure (see fig1 attached)

and when i export it to pdf

some people see it some of the items as transperent without fill (bad),

some with (good), and when opening the svg some fill some not. (open_svg_strange).
How can i fix it so everyone will see it with the fill ofcourse.

Make sure to enable "Rasterize filter effects" for export to PDF because Mesh Gradients won´t make it into PDF otherwise. 

It is enabled by default (see image) and what i showed is after i exported it

Where do check the PDF?

I'm not sure which app my coworker used. but he opened it on his ipad.
In either case, it shoudn't be like this. no?
When i open the SVG file i create on my phone, i see the "open_svg_strange", any idea why? i'd expect there to also not have this.

Looks ok here. Left: Inkscape file saved as PDF, right: macOS Preview.app. Pulse looks different but it´s just a rendering issue; vector data are alive:

if you are doing export as a pdf instead of save, it also works well for you?

But anyways, why when you open the SVG file, you do see the empty places? maybe if this is solved, that issue will be solved too