Satan creates Connector Tool in Visio
The combo of Visio’s Connector tool with the snap to and glue features are a tool of Satan.
To disable snap to and glue functionality:
1) right-click on the ribbon
2) Customize quick access toolbar
3) Choose from: All Commands
4) Add “Snap & Glue”
5) Open Snap & Glue options via the new button at the top of your Visio window
6) Uncheck Snap and Glue
And remember, CTRL+clickdrag on mid-point for straight leg, or SHIFT+clickdrag on mid-point for angle.