I don't have preview for documents in .odt, .ods, .rtf, .png, .ppt, .doc.
It works with .pdf, .docx, .xls, .png, .pptx.
Error message displayed on the preview pop-up:
{"entity-type":"exception","code":"org.nuxeo.ecm.platform.commandline.executor.api.CommandException","status":500,"message":"Error while converting via CommandLineService"}pdftohtml version 0.40