I second that. The trip ID should be listed on My Trips in the UR account.

Else, the itinerary number normally is on the top right hand corner of the Flight Overview section. The LX flights itinerary we booked, has 13 digits. Unfortunately LX not only does not have a waiver to cover May travel, but even for flights canceled by LX for Mar/Apr travels, LX flat out refused to refund, saying they would not process anything until after Dec 2020! There is a thread in LX forum on this. Some people have resorted to charge backs. AMEX seems the best immediately issued credit when chargeback is requested on the flights canceled by LX. Sadly with UR pts booking, there would be no such option - one of the perils to remember on the short-coming using UR pts to pay.