When you click Add Submission and nothing happens, and the submission is not added, it usually happens for one of below reasons:
1. Note text is formatted (copy/pasted from a document or email) or too long (Only 1000 characters including spaces are supported in your note.)
Solution: Type short note directly in the field or paste from a utility like Notepad to un-format text.
2. The file added is corrupted.
Solution: Add valid file. Be sure your file name does not contain special unsupported characters.
If these do not resolve your issue, please provide the email login you use for the site, project number, file(s) and submission note so we can further investigate.