Select Type Field Missing in Extensions Manage
From Joomla! Documentation
The Select Type field is missing in Extensions → Manage → Manage for updated sites. The field is displayed on fresh installs.
This pertains only to Joomla! version(s): 3.8.10
What is the cause
The file /administrator/components/com_installer/models/fields/type.php is being deleted from sites during the post-update processing.
How to fix
Update to Joomla 3.8.11 or re-install the file: https://github.com/joomla/joomla-cms/blob/staging/administrator/components/com_installer/models/fields/type.php in /administrator/components/com_installer/models/fields/