doesn't show Templates with empty Plain-Text for System Default -- started as of CiviCRM 5.69.1 (and probably 5.69.0)
Looks like the changes in CiviCRM 5.69.0+ may have caused Better Messages Template not to fully function. I can see the templates to select, including the sample data and whether they're modified. But, selecting any template to view has the bottom two content areas blank for any for the formats, i.e., HTML, Subject, Plain-Text.
Saw the following in the Apache logs:
AH01071: Got error 'PHP message: PHP Warning: Undefined array key "msg_subject" in /.../wp-content/uploads/civicrm/templates_c/en_US/%%02/029/0292F7C1%%MessageTemplates.tpl.php on line 155', referer: https://example.org/
AH01071: Got error 'PHP message: PHP Warning: Undefined property: CRM_Btrmsgtpl_Form_MessageTemplates::$_id in /.../wp-content/plugins/civicrm/civicrm/CRM/Core/Form.php on line 2087
PHP message: PHP Warning: Undefined property: CRM_Btrmsgtpl_Form_MessageTemplates::$_id in /.../wp-content/plugins/civicrm/civicrm/CRM/Core/Form.php on line 2087
PHP message: PHP Warning: Undefined property: CRM_Btrmsgtpl_Form_MessageTemplates::$_id in /.../wp-content/plugins/civicrm/civicrm/CRM/Core/Form.php on line 2087
PHP message: PHP Warning: Undefined array key "isAdmin" in /.../wp-content/uploads/civicrm/templates_c/en_US/%%00/004/004E38E1%%MessageTemplates.tpl.php on line 213
PHP message: PHP Warning: Undefined property: CRM_Btrmsgtpl_Form_MessageTemplates::$_id in /.../wp-content/plugins/civicrm/civicrm/CRM/Core/Form.php on line 2087', referer: https://example.org/
Have not yet investigated further.