I've had MultiBit HD do something similiar... where it won't activate the "next" button for some reason... I usually just click "previous", reselect that i want to restore and try typing the 12 words in again (NOTE: don't try and copy/paste it in either).

You can also double check your 12 words here: (NOTE: Run an offline copy to be safe!) https://iancoleman.github.io/bip39/

It even offers suggestions for mispelled words