Hello,
We have come across a few instances when dwg fileș do not load any longer in Draftsight when clicking on any dwg file in case DS is open / loaded.. 

If DS is not open / loaded, then clicking on an Abc.dwg file will open DS and a new No-name.dwg, but not the exisiting Abc.dwg file that has been clicked upon. So the Default Program to open DWG files has been properly set.

We experience this in both Mac and Windows versions of DS 2021.

Any advice how to overcome this issue??

PS. Uninstalling and reinstalling/reactivating the Draftsight does the trick, but is cumbersome.