Liquid/gas bridges are currently not selectable from the plumbing/ventilation overlays. The only way to select a bridge (e.g. for deconstruction) is to close the overlay and cycle through on the regular view.
This has worked fine until a few updates ago.
- build a liquid or gas bridge, and pipe segments on input, output, and another pipe going under the bridge
- in the corresponding overlay (F6/F7) try to select the bridge