I tried to change the login logo on all my child sites with the branding extension. I can upload and save the logo under “Extensions → Braning → Wordpress Options” without any problems, but the on my child sites the login logo is still the same from wordpress. The “the Overwrite General settings option” is not enabled for any child site.
Upon further investigation, we were able to find that the HTTP Basic Auth set on the MainWP Dashboard site has been causing the problems.
This security layer blocks requests when child sites try to get the uploaded image from the Dashbaord site.
It might be best to use the MainWP Clean & Lock Extension to set the same security measure without breaking other features.
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