Hello,
There was probably nobody think about html entities. Everything is saved in database, but at the moment you are displaying saved data, browser will change all html entities to single characters... So next time it is not saved.
I have simple hack for you to solve this problem. Find this file:
{project_root}/administrator/components/com_artiofusioncharts/helpers/helper.php - around line 780 is this code:
$row = str_replace(ARTIOFusionChartsHelper::getValueMask($match[1]), 'value="' . $match[2] . '"', $row);
Change it to:
$row = str_replace(ARTIOFusionChartsHelper::getValueMask($match[1]), 'value="' . str_replace('&', '&', $match[2]) . '"', $row);
I will let it check by development and we will also prepare repair for next version.