I'm pulling together an itinerary from TUS-AMD in Feb (Outbound Feb 2, Return Feb 12), ideally connecting through EWR on the direct flight EWR-DEL. So something like TUS-IAH-EWR-DEL-AMD. Round trip pricing on UA TUS-DEL-TUS in economy is reasonable (~$2K). I can add in the DEL-AMD flight on AI without any issues (booked as a multi-leg). But when I add in AMD-DEL, the fare basis changes to Y for the entire trip and the ticket becomes $10K. That domestic India segment is obviously not costing $8K, and on the AI website I can price both AMD-DEL one way, and DEL-AMD-DEL roundtrip for reasonably cost (<$200 RT). I've tried pricing as RT, and also multi-city in different variations on UA.com, and also google flights and ITA - all are doing this.

Any idea why adding a single AMD-DEL segment causes massive breakage? Since the non-UA booking engines are also doing this, I assume it's something in the fare rules, rather than a UA.com glitch, and so calling UA reservations is unlikely to work.

I haven't traveled to India before - is booking separate tickets here likely to cause me a problem? In both directions I would have a 4-5 hour connection in DEL. Am *Gold, UA 1K if it makes a difference.