In the attached save, I have a manual generator and 4 wires queued for construction. Stinky is carrying 300kg of metal to the build area. Despite that, the manual generator says it has insufficient materials for build. In addition. it seems to be reserving the materials twice, as I have 50kg of metal on the ground but my resource display says I have 0kg available.
Load the save and watch the materials available display. It will only go back to 50kg once Stinky supplies resources to the manual generator.