Hi,
I'm trying to see if manually adding the domestic connections on an int'l itinerary will have united's website price similar (lower) to some 3rd party (XP etc.) and ITA.
In the flight I'm looking at, I need to connect in ORD, however when I add this in, it shows:

Please correct the following 1 error(s):

• Double-check your dates. One or more of the flights on your trip is earlier than the flight before it. Check the dates for each leg of your trip

The second leg's date is highlighted in red which to me reads that the system cannot handle this. This is just a same-day connection, so it isn't earlier.

Is this a known problem?

Thanks