DWL Files not being created for certain DWGs

[CommonGroundIndustries]

We have a certain DWG files that, when opened, donot get DWL files created for them. The result is that it is hard for other users to determine who has the file locked. The file is being opened with write permissions and is locked as far as Windows is concerned, it is just not creating a DWL. I wonder if there is either something corrupted in the file or some kind of internal CAD file setting. Here's further info:

• The issue can occur locally as well as on the network. I believe this rules out network problems. But not 100% if some kind of network issue could have caused the file to be corrupted and then subsequently have the issue locally.
• The issue is intermittent. 
• Has occurred on two different computers.
• Has happened with two different DWG files - both were large around 15-17Mb.
• The file properties appear normal - not read-only, etc.
• The files themselves function normally as far as CAD is concerned - no other weird issues.
• AUDIT command does not find any errors. 

I've been a network admin for 6 years for a business that has about 15 full time CAD users and this is the first time I've seen this issue. And I've seen CAD do some weird stuff.

Any suggestions or advice is appreciated.

[pendean]

What is unique about this set of drawings exactly? I can't tell you've investigated much based solely on your post: is this a unique folder or drive (or server) location?
A locked-from-editing folder?
Your two users are on limited user OS accounts and do not have full read-write-edit-delete access?

FYI DWL files are created in AutoCAD (since WindowsOS) to service the WHOHAS command inside the program: look it up. it has nothing to do with file locking.

FWIW File locking for in-use files remains an OS function: there is nothing AutoCAD to help that unless the program is not registering correctly with your OS.