Has anyone experienced a Checksum error opening a document that Workflow has correctly processed as a re-name, move, template and metadata population?

Both the metadata, rename and move appear to have occurred correctly but the document throws a Checksum warning shown below when opened in the client.

I did some notification changes to an Imported 9.1.1 workflow in my 921 server 2008 32 bit VM, Exported it and imported it into the client's new LF 921 2012 R2 server I've setup and it appears to work except this error showing. The document image, metadata and filename are all correct.

Also the test input file brought by drag and drop via the client opens without error. existing documents from a test backup I restored also seem to open without issue or warning.

I have a case 167970 open with LF support but am on a tight timeline so I thought I'd see if there's field experience with this.

Thanks,