Hopefully you’ve been able to work this out. If not, do post further and we’ll see what’s going on.
Adobe XDDebbie Suzuki commented
Jan, when you say you aren't able to replace existing links do you mean you are trying to drag the wire to a different board? Are you clicking on the blue tab with the white > and dragging it to a different artboard? If so when doing that make sure the new target artboard is highlighted blue showing that it's what will be linked to. If you're able to make a recording of what you are seeing and send that to me: firstname.lastname@example.org that would be a great help too. Thanks for your help in narrowing down this issue.