Hi guys,
I am experiencing the exact same problem, the custom logo is broken as the header image and in the admin panel (also displaying 3 broken images).
However I am using this logo (referencing the URL) in the email notifications and there the logo is still well displayed. I see however that the URL pointing to the logo in these email notification is different though:
Email: https://sherlog.msf.org/storage/attachments/5649-logo-new.png
Site header: /osta/uploads/logo-new.png?1591096212