When I click on "personalization" in order to insert a field other than the name, no items appear for selection; rather, the 'person's first name' field is automatically added to the email. Can you help?
I took a look in your account, made a copy of an email you were working on and was able to insert personlization tag (which does default to first name) and with my cursor within the tag, change the tag from the drop-down menu above. I've attached a screenshot to share what I saw:
After inserting a personalization tag are you able to highlight it and produce the dropdown menu like in the screenshot? If you can't then it's possibly browser related and the best place to start would be to clear your cache and cookies to see if that helps.
I'd like to know if this is happening in a specific mailing, or is this happening across the board for you? If it's the latter then that would be the a further indication that this may be your browser, if not then please let me know which mailing you're working in so I can try to replicate the trouble you're having.
I hope those initial steps help, but if not I'll keep a close eye out for your response here :)