Connectors Do Not Glue or Route Correctly

If Connectors do not glue to any shapes when their ends are dragged to the shape's connection point, but they do glue correctly when using the Properties dialogs and using the Visio Connect Shapes tool, it may mean that Glue is switched off in the File.

Check the Snap and glue function is turned on in View > Visual Aids and click on the Expand icon.