RTF only converts when Kindle is attached
I have an odd problem. I'm using the latest version of Calibre with a Kindle and I'm trying to convert some RTF files to MOBI. When I select the files in the library view and hit convert an error "Failed to convert book".
What's odd is that if I plug in my kindle and hit "Send to Device" it asks me if I want to auto-convert before sending. I select OK and calibre converts the RTF file to MOBI with no problems. I'm baffled by this.