Using APM 10.7 SP3, when setting introscope.apmserver.ui.welcome.url as mentioned in
Results with a blank page after logging in.
Code Changes in APM 10.7. Due to several security vulnerabilities reported by customer, APM introduced Content Security Policy in 10.7 SP3 and this also affects the welcome screen
APM 10.7.x
https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP CSP (Content Security Property) Overview