I am currently using DraftSight 2021 SP0 for .dwg drawing creation and editing, and our machinists use AutoCAD 2004 to open the .dwg files and create .dxf files of selected entities within the drawings for machining. On 4/30/2021 one of our machinists started having problems using the entity select feature when creating .dxf files in AutoCAD 2004. AutoCAD displays the error "Unable to create proxy," and fails to create a .dxf file. This issue can be circumvented by creating individual drawings for each part that needs to be machined and deselecting the option to select entities to convert to .dxf. However, we try to keep all our assemblies and corresponding components in the same drawings for ease of access, and the majority of the older drawings I am using are laid out in the same way. 

Here are the specifications for the computer DraftSight is installed on: 

Dell Precision T1700

Intel(R) Cor(TM) i7-4770 CPU @ 3.40GHz

16.0 GB RAM

Windows 10 Pro 64-bit OS

NVIDIA Quadro K4000