Hi,
I run several blogs and all of them use the jetpack sitemap plugin, but there seems to be some html encoding issue with the text "Change frequency" when its translated (in my example to swedish) which in this case would be: <th>Ändra frekvens</th>
The error says undefined entity and its because the text does contain & in the beginning and that doesn't seem to be correct. Its on line 93 in my case, if that is of any use.
/ Tobias