The transformer in the image existed and powered my base for many cycles. It had two "natural" tiles under it. I replaced them and got "tile missing" despite there not being a missing tile. This persisted for a few minutes real time before I bagged it and reloaded.
Next time I build the transformer under it first and connected their outputs together, so that if this happened again I would be covered. It did not happen again.
The transformer is connected to powered heavy watt wire.