The link and vlink stuff has nothing to do with with your blank page problems. Get rid if the unnecessary attributes from the body tag and the error will go away.
The link taking you to a blank page is unrelated to the attribute errors (and really unrelated to Sigil). Mobi is very picky about where the anchor you're linking to is placed. The best practice is to not link to anchors (or ids) at all. Make your toc an entirely separate (x)html page and link directly to it (no url fragments). Linking to the ids of headings will get you into trouble with mobi every time.
If you must link to somewhere in the middle of an html page, link to an anchor tag
placed before any block elements (especially any
styled block elements).