Hi Daniel,
URE “Admin menu blocking” works with the static admin menu created by plugins in a classic static way. URE saves a copy of the full admin menu available for the ‘administrator’ and then allows to select what to hide from the list of those menu items.
Learndash builds some submenu dynamically in relation of what page/post is selected currently. “Transactions” menu item is between them. It’s protected by ‘manage_options’ user capability:
define( 'LEARNDASH_ADMIN_CAPABILITY_CHECK', 'manage_options' );
Clarify with ‘Design->Customizer”, which you can not hide. Is this menu item created by your custom theme? In this case I need access to the theme source code .zip in order to try repoduce the issue.