Was your dog sedated for the procedure? Dogs who are sedated are often groggy for some time and they may not drink as they normally do to trigger a need to pee.
It can be that your dog is painful (torn nails can be very painful) and therefore walking around in the yard triggers some pain that is interfering with her need to go potty.
On the other hand, it could just be that walking around with a bandage is keeping her focus off her need to potty.
Maybe you can try again a little later, and hopefully by then, her need to potty will supersede the sensation of pain. You may also want to phone the vet if she seems to be in pain or discomfort for some pain medication.