Parts of 3D model disappears after saving

[Anonymous]

Hallo, I have a problem with 3D-modelling in AutoCAD 2019.

I modelled a 3D object of a house with regular 3d-tools, saved it, but half of the modell disappeared after that. 

As you can see, in the files preview we can stil observe all of it, but in the program itself after openning the groundfloor doesn´t exist anymore. 

The file is attached.

[pendean]

Your file is looking for 4-XREFs, are you sure you have those too?

Otherwise there is nothing in your file beyond what you already have, and those really small 3DPolyline objects.

[Anonymous]

The 4 refs are just .pdf files that I used as underlay for modelling, they were deleted long before the last saving.

How disappeared the groundfloor object, it was there before the saving. And was "replaced" somehow with those strange little polyline objects…? 

[Erense]

When you purge the drawing the 'polyline' objects are removed. Tehrefor the is nothing else than these 4 solids.

You best check if you can find an old back-up file to restore.

This Drawing is not complete anymore.

Perhaps you accidentally erased the groundfloor instead of the xref's. (because the are still linked)

[Anonymous]

Hallo, thank you for your reply. But does it purge automaticaly, because I never used this command here? It was just a simple object made from 3d-solids and redacted with boolean operations. It is unfortunatly not the first time, it happens constantly. Could it be a lokal computer problem?