I noticed occasionally that the resource-centric icons lose their dragging functionality. The result is that when I drag the icon, the icon itself is moved and no associations are created. However, clicking on the icon produces the expected result of the popup appearing.
Unfortunately, I can’t reproduce this glitch in a reliable manner but I just wanted to give a heads up. The current workaround for me is that if I encounter this behaviour, I can just save the project and functionality seems to be restored. Maybe I should just save more often.
Next time, I’ll try to remember to get a screenshot so this is more clear.