We also didn't submit the OWP checklist (which was actually an oversight), but I've seen posts on these forums that there are others who also didn't submit an OWP checklist and got AOR and their OWP as scheduled. A search of these forums reveal that there are members assuring others who also didnt include the OWP checklist that it is not required for PR inland sponsorship. I really hope that's correct. Fingers crossed!
As a precaution, I've printed out the checklist and the required documents in case the application is returned and I can send everything out again ASAP.