[Joomla 4.0] Cannot access/set user permissions

Clicking the Joomla access control link (/administrator/index.php?option=com_config&view=component&component=com_civicrm) via either Civi (administrator/?option=com_civicrm&task=civicrm/admin/access&reset=1) or Joomla (administrator/index.php?option=com_config#page-permissions) gives a fatal error. Without setting ACLs, the front end Civi links won't display - so this looks like a blocker for Joomla 4.0 compatibility.

According to Joomla 4's debugger the issue is:

Compile Error: require_once(): Failed opening required '/Applications/MAMP/htdocs/Joomla_4.0.2/libraries/joomla/form/fields/rules.php' (include_path='.:/Applications/MAMP/bin/php/php7.3.7/lib/php')

FatalError in /Joomla_4.0.2/administrator/components/com_civicrm/civicrm/joomla/libraries/joomla/form/fields/civiperms.php (line 6) <?php defined('JPATH_PLATFORM') or die; // for some reason Joomla doesn't autoload JFormFieldRules in this context require_once JPATH_SITE . '/libraries/joomla/form/fields/rules.php'; class JFormFieldCiviperms extends JFormFieldRules { /** * @var CRM_Core_Config