Hatch patterns wont get attached to 3D geometry DWG exports. They will only will be attached to a 2D (place your 3D on a sheet and export the sheet). It looks like what you are using is a 3D Geometry CAD?
Can someone else verify this - I just tested and it didn't attach any surface patterns to the walls on a 3D export but did on 2D.
For 2D issues... I'd check/test a couple things.
#1 Try with a different PAT file. AutoCAD has stricter .PAT rules and may be not allowing the pattern to show up. This most likely is not the case as that looks like a simple one.
#2 Check your view scale settings and all that in CAD... it might be there, the settings for units or something else might be way off and you can't see it replicate in that short distance.
#3 Check your export DWG/DXF settings under Walls > Surface Pattern. See where that is going and anything that might look funky there.
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