Dogs might seem to forget their training when asked to perform familiar tasks in unfamiliar situations. The behavior you taught might be very specific to certain scenarios.
Help your dog increase his stay fluency by imagining different scenarios where a stay would be helpful and work towards achieving them as a team.
Just like a foreign language learner might struggle in a new country, dogs can struggle with commands in new environments.
Sometimes, the environment can trump the trainer. Your dog might be too distracted by the surroundings to respond to your commands.
Ensure your dog's responses are close to perfect in a familiar environment. This foundation training is crucial before moving to more distracting environments.
If your dog seems to be ignoring a command, consider physical comfort. Some dogs might be uncomfortable sitting on hardwood floors or near noisy equipment.
Understanding the how and why behind the refusal can make life easier for both you and your dog.