Hi , just my experience updating my PR to Canadian Citizenship on my Nexus ,went to Pearson YYZ about a month ago , no appointment needed walked in sign the book and was called upon the CBSA officer took all my info copies Canadian passport and Citizenship certificate and kept my Nexus card and told me a CBP officer comes once a week takes all the documents and goes back to the states and have to wait till the info is change and it will take a wile ,Canada side is updated keep on checking your , So I decided to call the CBP whirlpool nexus office in Buffalo NY to inquire how my citizen info hasn't been updated on the US side so I can order the new card online , the CBP officer told me the fact the Canadian Nexus officer in YYZ told you a American CBP officer takes documents there is " false you have to come in personally to any enrollment center bring your Canadian passport and the Citizenship change will be made" , so I say after the Caribana jump up and had nothing to do yesterday wife and I decided to take the road trip to Buffalo, Whirlpool since they close 8 pm on a Sunday ,crossing the boarder into the USA was no problem first time using my Canadian Passport all was asked purpose to visit "to update my Nexus Citizenship at the enrollment center".
At Whirlpool enrollment center not busy at all just one couple was there doing the process. The CBSA officer took my passport alone not even the Canadian certificate make sure it was updated and hand it over to the USA CBP officer , she took 10 mins to update my Citizenship info in the portal and it will take 10 mins to show up in my profile . Also when I'm applying for the new card online use the Lost option and not the change citizenship line ,it will better that way because I will have to return in person to verify my address . Returned last night back home in Toronto ,went into my profile and all my info was updated and ordered the New car $25 US or $33 Cad. I will advise going to Person airport to update your nexus citizenship don't believe anything the officers says there you will be waiting forever for the usa side to get your info ,go into a enrollment center where both CBP and CBSA officers can update it less than 20 mins time , will update you guys when I get the updated card in the mail.