Madrid users are not allowed to configure a custom banner image to display, even following the provided documentation:
Steps to Reproduce
1 - Navigate to "Basic Configuration UI16".
2 - Define a new image for "Banner image for UI16".
3 - Save.
4 - Refresh the page. Notice the default ServiceNow logo is still showing.
5 - Navigate to "Basic Configuration UI16" again. Notice the banner will display, but as soon as the page is refreshed, the ServiceNow banner will come back.
This problem is under review and targeted to be fixed in a future patch. Please review the Fixed In section to determine the latest available patch your instance can be upgraded to. You can Subscribe to this article to receive notifications when more information will become available.
As a workaround, please apply the solution documented in KB0743696 - How to update the banner image or the company logo in UI16.
Related Problem: PRB1328367