Unfortunately it turns out that Google Docs, Sheets, Slides, etc. have file extensions that we currently do not support. While we look into how to fix/support this, as a workaround you can download the files and then drag/drop or upload them back into your Google Drive account and then you should be able to print them. Sorry for the inconvenience! Look for a post on this thread for an update on when we will have a fix for this.