Short ascii names not generated

I am working in Lectora 6. I have 'Generate short ASCII HTML page names' checked in my publishing to HTML settings. Sometimes, it publishes with ASCII names and sometimes it publishes with names like Pagexxx.html. I do not get any errors related to page names when I do the Error Check. (I only get one in Checking Resources that tells me my movie clip is large and 2 in Checking Pages that tell me Action GoTo Previous Page and Next Page have unresolved destinations). I have gone through my course and do have some large page titles - perhaps that is the problem. Is there a max title that will translate to a 'short ascii' name? That is the only thing that I can think of.