Can you please share with me the Chaos Cloud job where this happens? If it’s more convenient for you, you can do this in a direct message to me here in the forum.
And just to follow up here as well, for the benefit of other people who stumble upon this.
V-Ray runs the Denoiser only when the end criteria are met, i.e when the Chaos Cloud job has completed. In this case, the jobs have been stopped manually by the users as they are happy with their current output quality. We have logged an issue in our project management system to start running the Denoiser even when the job is stopped by the users without meeting the end criteria. The issue number is CLOUD-1152.
As a workaround, you can download the output image and run the standalone Denoiser as explained here: V-Ray for 3ds Max