I just started a new game with 0.12.27 without mods, created a steam engine setup with a working boiler and water, put poles next to the steam engine, but it shows the "not connected" icon.
There were no consumers connected yet, the network shows 0W, but the steam engine is clearly connected.
When I put some consumers in the network it works and the icon disappears, but isn't the "not connected" icon irritating when the setup was connected properly?
Screenshot