Love these type of problems...
First, why a dxf as AC can open dwgs fine?
The reason that nothing is showing up is that there is nothing drawn in AutoCAD's model space, all the lines were drawn on Pspace so when you import into AC all you will get is a blank Story. Even if the file was a regular dwg.
To open the file all you have to do is open it using PlotMaker and making sure that you choose "Append Paper Space Layouts to Book". From there you can save it as a dwg and open it in AC.
BTW this is not AC's fault since this is not a standard way to draw in AutoCAD. The equivalent in AC is that the draftperson instead of drawing in AC drew all of the project in PM and then you wondered what happened to all the 3D info?
Attached is the DWG file as it is supposed to be... it will import without problems into AC. Also be sure to verify the dimensions, I don't trust dwgs that have these types of errors without double and triple checking them for other problems.
Eduardo Rolón AIA NCARB
AC27 US/INT -> AC08Macbook Pro M1 Max 64GB ram, OS X 10.XX latest
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