This was a genuine defect. Thanks for pointing it out. It’s fixed in the latest version.
I have implemented a kind of visual feedback in the latest version (0.9.68). When the pointer is near a snapping point, the snapping point will glow up with a red indicator. Pressing alt will snap the pointer to this point.
For this to work, you will need to enable the Snap Indicator option from Snapping Preferences in the add-on dialog (by default the option is unchecked). You can also change the size of the snapping point (just in case if it’s too small for your taste : ) as well as the snap distance.
