Good morning, @sourabhjain-itsa.
Thanks for reaching out to the Community for support and sharing your concerns. I'm happy to lend a hand.
I recommend we try some basic troubleshooting steps, such as clearing the cache from your web browser. Web browsers collect cache to save time when loading repetitive data and images. Over time, these files can become outdated and corrupted, causing issues like adding your new sub-customer. I've included links for all supported browsers that contain the steps to clear the cache below.
Once you've cleared the cache, you'll need to close the browser then reopen it for the changes to take effect.
Please let me know if you have further questions or concerns. I'm only a Reply away. Feel free to reach out to the Community at any time. Take care!
