Just checked it. You template must be edited. Follow is fixed for IPS 4.4:
{template="follow" app="core" group="global" params="'tutorials', 'article', $article->id, $article->followersCount()"}
See if the REVERT button is ON in this template.
Same for the category view:
{template="follow" app="core" group="global" params="'tutorials', 'category', $category->_id, \IPS\tutorials\Article::containerFollowerCount( $category )"}
Btw, paying attention, your error seems to come from MEMBERS COUNTRY, which there was this issue indeed but this is already fixed. Download the latest version.