Your comments

Sorry to hear that. I will need more information to debug this issue though. What is the backlog ID (it's the number in the URL), and which story is this happening with? Can you confirm this happens with specific values or any value? 
There is no automated import unfortunately because we have found everyone tends to have different requirements making a one size fits all solution unfeasible. There is however a documented APIA you can use if you wish. Sorry we don't have a solution for this. 
Unfortunately we find that this is typically out of our control as email spam filters and firewalls sometimes block emails.  Have you tried sending the invites to an alternate email address on a different domain?
Hi, I believe I have found the issue and fixed it, it's a known bug with the latest version of Ruby and Rails that we are using.  Could you please try again?
Hi Bryan and Mdrwells, I am sorry about this.  Can you please send me the backlog ID (it's in the URL when looking at it, don't worry, no one else can access it), and the story in question, I'd like to take a look.
Hi Bana

Send me your email address and I will send you a link to a document where we need a few words translated for us.

Matt
That's a nice idea, and I believe we can actually do that as we keep the history.  It's simply a matter of building a UI front end for this data, we will certainly consider it.
Ok ,thanks for the feedback, we'll consider that.
That is correct, out of interest, what do you think would be a suitable way to delete ACs without cluttering the interface unnecessarily?
Oh, that is not good.  I will see if I can get that fixed as soon as possible.