My assumption (and it’s just that, an assumption) is that receiving the I-797 does not create any *new* complications, but they’re saying “hey, traveling on an expired PR card plus extension letter is not ideal, and you’re very, very close to getting your new PR card, so just hold on for a couple weeks if at all possible.”
Later on the letter notes that if “an emergency arises” that requires international travel, you should get a passport stamp from your nearest USCIS office.
Hibernica got a reaction from tootiespookie in I-751 August 2017 Filers