Hello everyone! Longtime lurker, first time poster, and hope you can help.

Work have booked me the following trip:

LHR-YYC - BA
YYC-IAH - Delta operated by Westjet
IAH-LHR - BA

I had a notification through the BA app that online checkin for the YYC-IAH leg was now available, but when I click through, BA tells me to contact the airline directly to check in.

Would this be Delta or Westjet?