@ willfitz53 asked: "What is country code xx found on K-3 forms?"
First, please be aware that I'm not a tax expert, and I'm not affiliated with TurboTax/Intuit. I usually help fellow forum members with personal tax products, and I know nothing about partnership returns or other business returns, including Schedule K-3. But I do know how to search the Schedule K-3 Instructions at the IRS website, so I'll pass along what I saw there just in case it's what you need.
I went to the IRS K-3 Instructions page linked below and searched for "xx" using my browser's "Find on page" function. And I found one mention of that xx code on the page. You'll have to look at it yourself, since it's kind of complicated and mentions a specific part of the K-3 by Part and Column letter and tells why an xx code may be seen there. So you'll have to look at that instruction there and see if it explains what you are experiencing.
NOTE: At that page below do not use the IRS search box that's in the upper right--that searches the entire IRS site. Display the page and then use your browser's "Find on page" search function.
Partner's Instructions for Schedule K-3
https://www.irs.gov/instructions/i1065sk3
