Originally Posted by onthesam

Hah -- thanks for the optimism ! Actually, when @jsloan says something is a bad sign, I respect that. Thanks for chiming in.

If your theory is correct it sounds like LX may have dropped my ticket and reservation prior to my call this evening as the agent insisted neither pax had a confirmed seat on LX, a story which jives with the inventory available at the time I called. After some light banter with the agent and a few minutes of hold music, and despite a lack of visible (to me) award inventory, the agent was able to get us back on both original LH segments with two new ticket numbers issued.

Interestingly, on UA.com everything looks good, including the ability to select seats on LH, except that the 'View Receipt" button generates an eTicket Itinerary and Receipt that still shows the LX flights, but now with the new ticket numbers.
When I pull the record up on LH, it shows both the LH and LX flights...