I certainly have no idea about the actual reason but every time and finish writing a post and hit that magical ;-) "publish" button nothing happens. In fact the post gets a "Scheduled" notification message attached to it. I thought "what the heck!" and made sure that I haven't scheduled anything and make sure at the scheduling options area is saved as "Automatic" but still I can't publish a singe post!. Although interestingly enough, if I schedule the post publishing date to a date before the new GUI implementation took place, then the posts get publish (which is certainly not a workaround at all).
But luckily we can easily disable the this new GUI since it's still in the blogger in Draft (where you got the change to taste things at their beta stage, yikes :D) all we have to do is disable the "blogger in Draft" your default blogger interface.
Anyhow, if you're new and think that Blogger platform sucks... let me tell you one thing in all honesty (and humbly). I love blogger!, it's bloody easy to use, pretty solid platform (usually) + filled with services which are absolutely free but as the saying goes "Shi* happens".
And I did look at the blogger help forum but after the new GUI implementation I didn't see any "major" issues so I guess they've done a pretty good job because at the moment it seem to be working quite nicely for the majority (which is the best that we hope to achieve anyway).
So all you gotta do is just log-into your Blogger-in-Draft account and from the upper-right corner uncheck the box that says "Make Blogger in Draft my Default". Then log-out and log-in (not always but you may have to clear the web browser cache) and you're done!.
That should do the trick.