Checkout bug

I have a problem with checkout. In case I go through checkout without registration (guest mode) - everything seems to work fine.

If I log in into system - on the Step 2 of checkout it suggests either to select address from a list I have in my account or to enter it manually. However - continue button does not appear no matter what I am doing!

Please help! This seems very strange to me that I could not find same bugs on the forum...

Thanks in advance!