It might be a work protect, popup or generic browser issue. Can you send a screenshot demonstrating the problem? What SAP release are you on, share the exact version including SP and patch levels. What browser are you using, what version? What URL are you using to access the portal? Is it in FQDN format?
See if the below notes are relevant to you. Especially, see if DSM Logger helps you to solve the problem.
https://service.sap.com/sap/support/notes/596698
https://service.sap.com/sap/support/notes/1331353
https://service.sap.com/sap/support/notes/1334956
https://service.sap.com/sap/support/notes/1401567