Generating plain text option is ignored!

I originally uploaded a word document a few months ago into the DL via a zip file with many other documents. At the time, the text conversions weren't working so I left this document as 'submitted' and figured that I would amend the submission once everything was working again.

I have now decided that I don't want the word version available. I only want the pdf and a (generated) text version available instead, so I amended the submission form and deslected 'file downloadable' for the word document and I added a pdf and also enabled the text conversion option. I amended any other details and then submitted. The DL confirmed the doc and pdf but it didn't confirm that a text conversion had happened. Once available and published, the only link available is PDF, despite the fact that if you go back into the DL and look at the form is still has the 'generate' plain text version enabled, but it is clearly ignoring it!

The only way to resolve this is to delete the whole thing and start again, which isn't ideal.