Sketchup is not letting me import .dae from Blender, when I do it comes up with a blank box
And what shape was it in Blender, wasn’t it still a box? What is different about it from the one imported in SketchUp?
I tested with the default Cube from Blender, to which I added a material on which I drew a few colored lines
imported as DAE
imported as OBJ (before exporting, I saved the texture - UV Editing > Image > Save as…)