Illustrator gets a bit weird when I hold down shift to click and drag an object.
When I hold down shift to click and drag or when I hold shift+option and drag to copy, the object gets stuck. I have to take my finger off the shift key to move the object in place requiring an extra step to align.
Rafael Winniger commented
This is a known bug and it is presumably fixed in one of prerelease builds. You can join the program and update your Illustrator if it bothers you strong enough.