I have not seen anything that would block it from the government regulations as long as it is within 24 hours. Airlines are getting more cautious on separate tickets, so that could be a driver if this is a split ticket.

​​​​​​I might try to see what a second agent says, and be sure ask with specific flight information, JL15 to JLXX on specific dates. The more specific the question, the more specific the answer.