CS-Cart has posted a bugfix for the blocks issue, where the blocks are not saving correctly after configuring them.

According to the fix you need to edit the following files:
/core/templater_plugins/modifier.to_json.php

Replace this code:

$is_list = ($akeys == range(0, sizeof($akeys) - 1));

with this code:

$diff = array_diff($akeys, range(0, sizeof($akeys) - 1));
        $is_list = empty($diff);