Hi,
looking to the objects inside the dwg-file you'll see types not available with plain (Vanilla) AutoCAD, like "AEC_WALL":

And that can be one source of your issue! _WBLOCK means it has to create a new drawing and within that drawing it has to create the same objects, as AutoCAD itself does not know how to create an "AEC_WALL" it's limited to do that.
You might try to run command -EXPORTTOAUTOCAD (instead of _WBLOCK) as this command explodes the AEC-objects to AutoCAD block-references, maybe that helps to get it working.
BTW: When you say that WBLOCK is crashing AutoCAD, which options in the WBLOCK dialog did you use? (select objects or entire drawing)?
With that size of drawing I would have split it to separate dwg-files and use XRef technology to get a combined view. Opening 350MB files is not what AutoCAD "likes" 😉
- alfred -
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Alfred NESWADBA
ISH-Solutions GmbH / Ingenieur Studio HOLLAUS
www.ish-solutions.at ...
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CDay 2026------------------------------------------------------------------------------------
(not an Autodesk consultant)