Thank you for bringing this to our attention! I am sorry to hear you cannot upload your file of contacts as easily as you should. Are you receiving any error messages? Have you tried saving this file as a CSV instead? If you can please email us this file, along with your username and a reference to this post, we would be happy to test this for you. You can send these details to social_support(at)constantcontact(dot)com.
I fixed the error myself. But your dev team has missed another opportunity to do simple error checking that would have kept me from having a problem in the first place. Without getting technical, let me just say its a little embarrassing that your import routine could not have been a little more robust. I sincerely hope you folks recommit to quality because as of a week ago, I joined the team as a customer. I'm on the CC bus. I want the journey to be mind-blowingly great, not dopey and lagging behind the times.
We're always working on improving parts of our system, though of course all improvements take time. If you can tell us what was causing the problem with your import, I'll be happy to track your feedback and pass the fix along to our design team, so that they know what needs to be done in the future.