Perhaps this has already been signalled by others, but I have discovered one specific occasion, where the error message 'the object reference does not refere to an instance of an object' (or words to that effect) ALWAYS occurs and the word count is set to zero, necessitating the relevant file to be imported again. I have tested it extensively.
It always happens after running an analysis on a file, where two or more segments have been merged across paragraph ends.
If this is already known, I apologise.
Best regards,