Hi! Did you recently create your website? Or are you uploading the design. I can help you with this, I've experienced it before.
The website is ready and I've uploaded the index file to the directory for that subdomain just to test it out, but it doesn't seem to have an effect.
Welcome to GoDaddy Community! That would usually happen if the subdomain hasn't been properly set up to point to its own directory. To my knowledge, subdomains and addon domains do not get their own "coming soon" page, which suggests the subdomain isn't pointed toward the files you uploaded. If you can provide the actual domain and subdomain, someone may be able to give you additional guidance. For your connivance, check this out HERE. Otherwise, I'd recommend getting in touch with our support team so they can pinpoint where the issue is.
I have also experienced this since both on my account and one of my clients'. Let's hope they get this sorted out as it's driving me nuts