adding target="_top" to my link tag did the trick. The new code I used is:
<a href="#anchorlink" target="_top">Navigation</a>
I also found that Jive (v 188.8.131.52) did not like anchor names with hyphens in them. All the links I had using hyphenated names (e.g. "two-words") were being rewritten incorrectly, whereas any which didn't (e.g. "two_words" or "oneword") were left alone and worked.