Console offers tons of errors and warnings etc, but nothing that looks like it might stop the customizer from not working. In the default view I get these jscript messages:
JQMIGRATE: Migrate is installed, version 3.4.1
load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2 An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing.
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
$e @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
append @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
ce.fn. @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
run @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:6
initialize @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:6
o.Class @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:4
i @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:4
i @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:4
refresh @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:6
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:6
u @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:10
setTimeout
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:10
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:10
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=heartbeat,customize-base,customize-controls,customize-widgets&ver=6.7.1:6
e @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
t @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
setTimeout
(anonymous) @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
c @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
fireWith @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
fire @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
c @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
fireWith @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
ready @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
P @ load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,wp-hooks,underscore,wp-dom-ready&ver=6.7.1:2
/?customize_changeset_uuid=441b4398-376d-4a17-9ba5-9ee769fe828e&customize_theme=hueman&customize_messenger_channel=preview-0:1 An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing.
jquery-migrate.min.js?ver=3.4.1:2 JQMIGRATE: Migrate is installed, version 3.4.1