I have made a simple design for tinkering with the ne555. It works as expected:

Then I wanted to add a few things, starting with a switch. Upon adding it, I get this:

This seems pretty odd to me. The part I added is connect to one leg of the NE555. But it is not connected to anything else. So this warning should not happen. When I move the switch one contact point to the right (so it is not connected to anything) the warning disappears.

Strangely, when I switch it off there and move it back, the warning does NOT appear. The warning DOES reappear when the switch is on.