These are issues with my upgrade site from 5.4 to 6.1 but also on a FRESH created website 6.1).
Can you please confirm that these are bugs or at least help me find out why it isn't working.
I am glad you were able to find the problem yourself.
There is a bug in the radio buttons control. If you don't click on the "radio" itself but click on the label this doesn't changes the ratio selected value and the selection of custom confirmation page is lost.
It is a known issue with the radio buttons and happens only under Firefox. Under both Chrome and IE10, the problem could not be reproduced.
Please excuse me for the inconvenience caused.