Since you are already a PR, you need either a PR card or PR Travel Document to board a plane and fly to Canada.Same situation here. I have already booked my flights and I came to know about this. I have my copr waiting for PR card. I have a valid TRV and WP. Did you gather any more information?
Generally speaking, work permits and TRVs are automatically canceled in the system after you become a PR and the airline can see this in their systems. From time to time people have been able to board flights using their old work permit and TRV, but it's very individual and up to chance / luck. You won't know until you get to the airport and try to board the plane. Overall, it's best to assume the work permit / TRV are no longer valid in the system and you can't use them to fly. If you plan to try, make sure you have a back-up plan if you are refused boarding.