The Jupiter people figured out the issue, thanks to your initial troubleshooting. In case it helps, here’s their reaponse/resolution
I went through /wp-content/plugins/event-tickets-plus/src/Tribe/Meta/Field/ folder and editted Abstract_Field.php line 237:
$name = $tickets_plus->plugin_path . ‘src/admin-views/meta-fields/’ . sanitize_file_name( $this->type ) . ‘.php’;
to
$name = $tickets_plus->plugin_path . ‘src/admin-views/meta-fields/’ . $this->type. ‘.php’;
And it seems to be working fine now.
It was exactly render_admin_field() function.