The fix is included in manageiq-ui-components 1.0.9 https://github.com/ManageIQ/manageiq-ui-classic/pull/3379
Following the reproduce steps, I set a default value to a radio button (see screenshot) and saved, then edited again. The defeault value for the radio button is still not rendered (see second screenshot). The black dot should be on value "Two". The default value is saved, I can see it when editing the radio button in tab Options, it just isn't rendered on the dialog edit page.
Created attachment 1395248 [details] Set the default value for radio button
Created attachment 1395250 [details] Radio button still has no default value rendered
Erik, this looks like the same issue I've been fixing in https://github.com/ManageIQ/ui-components/pull/251
Thanks Roman, yeah I just pulled the latest and it appears to have fixed it. Antonin, please try with the latest build, it should be working now.
*** This bug has been marked as a duplicate of bug 1531571 ***