Can I run the WIP Value report as of a date in the past?

The WIP Value report can only be ran as of today's date.  This is by system design.  

The reason why you can only print the WIP Value report as of today's date is because you can do actions in the software today (such as re-open a closed job) that will affect the WIP Value if you print it as of a past date.

That being said, you can print the Balance Sheet as of a date in the past, and this may give you an approximation of what the WIP Value was at that time but because of the time-phased nature of how current transactions can affect this information is may not precisely reflect your WIP value as of that date.

You can print a Balance Sheet by going to the menus GL > Reports > Balance Sheet in DBA.  Before running any GL reports it's always recommended to post all transactions by going to GL > Batch Posting.