I think I'm missing something quite basic about Visio. I can't add connectors between shapes. I can create connections that appear to be attached to shapes, but when I move the shape, the connector endpoints stay where they were.
I have found instructions in the app's Help, which seem to correspond to this Microsoft support page. Where that page says I should position the Connector tool over the center of the first shape until a green box appears, I never see a green box. I can't get dynamic or point connections to work.