Civix doesn't seem to work with Joomla! 3.9.3. According to this, Joomla! 3.9.3 doesn't allow loading of phar packed files. When I try to run civix, I get the following exception error in a red panel:
Unexpected file extension in "phar:///usr/local/bin/civix/bin/api/class.api.php"
I reverted to Joomla! 3.9.2 and civix works again.