Strange misbehaviour importing PDFs

Hello everybody,
I have encountered a strange misbehaviour when importing vector graphics via pdf.
It seems that holes in a shape were not imported. Instead the hole gets closed.
I tried nearly everything to solve this (flatten the graphics, write as .ai, try several settings for the PDF) but nothing works.
The only thing that helps a bit is, to create a small gap to all enclosed holes, so that they are not closed anymore.
In case of this simple vector this may be a suitable solution, but if the vector gets any complexer this will not work anymore (without having a lot of extra work).
I made the vector with affinity designer and tried the same with adobe illustrator. I’m importing with harmony 15.
Example ist attached.
Does anybody have a workaround for this?
Best wishes

Import Problem.JPG