I am unable to open recently saved workplaces. 

I am getting the Error : the given path's format is not supported message for any newly saved workspace.

Exact steps that I am following to reproduce this:
Open a couple of log files.
Merge them by double clicking and saving them - does not matter if I set a custom name or not.
Save Workspace.
Close workspace.

When trying to open the workspace again - the error pops up.

I've re-installed the app. I've changed the Working Directory via settings. Error still persists.

Thanks for the update.  I have now been able to recreate the issue and am confident the implemented fix will resolve the issue.  

This problem looks to be specific to opening compressed files through a workspace.  I was not able to recreate the issue with a *.log file.

Toby