Add cloud details wizard seems not working

Running Fuse IDE 2.1.549 and build -084 of Fuse ESB Enterprise (full version). WIth a fabric started in Fuse ESB, try to Add Cloud details, but the dialog says " An error occurred while setting the value." for both the Identity and Credential fields. Has anyone else encountered this issue? It doesn't matter whether I enter the characters manually or copy them from a text file. The dialog's OK button remains grayed out, leaving only the Cancel button active.

Is this a bug, or can I resolve it somehow?