Null pointer exception when executing 2013 workflow

I am fairly new to the SharePoint 2013 product, so please be gentle. My company has recently installed and setup SharePoint 2013 (no users yet) and we are trying to get workflows to work. However, we keep having issues with the 2013 workflows. The most recent of which results in the following error:

RequestorId: 895b6ad6-83b4-4156-0000-000000000000. 

Details: An unhandled exception occurred during the execution of the workflow instance. 

Exception details: 
System.ArgumentNullException: Value cannot be null. 
Parameter name: 
Input at Microsoft.Activities.Hosting.Runtime.Subroutine.SubroutineChild.Execute(CodeActivityContext context) at 

System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager) at
System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation)

The workflow that I am creating is very simple. It consists of two document libraries: Documents and Template. I have a .docx file in the template library that I would like to move to the documents library. I execute the following workflow:

Log 'Starting to Copy' to the workflow history list

then Copy document in 'Current Item' to 'Documents'

then Log 'Finished Copy' to the workflow history list

Transition to Stage:
Go to 'End of Workflow'

This is as basic as it gets. We have SharePoint 2013 with SP 1 installed. We have the Workflow Manager 1.0 with the following updates installed:

and I have tried the following:

• Restart SharePoint server.

• Created the exact same workflow as above in 2010 workflow. This worked flawlessly. The 2010 workflows executes without a problem.

• Tried different document types and different subsites. Not fixed.

One more thing to add. I've had this code working before, the thing is we made a lot of changes and patch updates. I am guessing that maybe that it is one of the workflow manager updates that broke it? Is that a possibility? Anyone have any thoughts on what I can do to fix this? Also, is there a way I can find out the correlation ID? I can't find anything in the logs.

Thanks!