There were changes made to bring in the concept of Work Order (document) characteristics as opposed to Item characteristics on a Work Order. Subtle difference I know, and it needs to be clarified so it is more intuitive to understand.
For an Item characteristic to appear on a document (S/O, W/O, P/O etc.) it must be checked as "Used On" Items plus "Used On" the documents that they should appear. This allows you to configure item characteristics that are applicable to purchasing but nothing else, or applicable to manufacturing, or applicable to the sales process.
A characteristic marked as "Used On" a document but not used on an Item is a document characteristic only.
These changes allow characteristics to be used of all manner of things. So you can have characteristics on a work order completed unrelated to the item.
Please check your characteristic configuration. I hope this helps clear up any confusion, and improvements are being planned. Please provide more details if you are still having issues, and we can determine if it is a bug (known or otherwise).