At nowiki I often observe that the hovercard show up, but when I immediately click the link it will fail. I wonder if the problem is that the hovercard cover the link when it is inserted, and then are adjusted, but a click on the link before it is adjusted will fail. I have also been wondering whether the hovercard overshoots the edge sufficiently to interfere with pointer clicks, visually it seems to be inside the link area.
One workaround could be to increase the z-index for links and place the hovercard on a slightly lower index. That would give the link precedence, and thus avoid the problem.
This task was previously added as the comment {T68240#2962488}
I have asked the community at nowiki (w:no:Wikipedia:Torget#Hovercards) whether any other users experience this problem. I'm currently using Firefox 50.1.0 on Ubuntu 16.04, and occasionally on Windows 10.