In the file with the seemingly empty Type Layers what happens if you Select All and align to the vertical and horizontal center?
Image > Reveal All?
Genius - you may the rest of the day off!!
I, on the other hand, am a complete idiot. File 1 is 1500px deep and File 2 is 1000px. Duplicating layers in this way places the layers EXACTLY in the position they were in the original - in this case 300px below the canvas. Revealing all - weel, reveals all
A thousand thanks