Ubisoft's Verification Email Never Arrives Despite a Valid New Address

Since I no longer have access to the email address registered on my Ubisoft account, I want to change my email address through the website. The verification code arrives without any issue to the phone number registered on my account; I enter this code and type in my new email address, but even though the system says "we've sent the code," no verification email ever reaches my new email address.
I've been experiencing this problem for months, and despite trying repeatedly, I haven't made any progress. I can use the same email address without any issue on other platforms like Kick and Steam — when I receive test emails from these platforms, I don't have any problem. I believe the issue isn't coming from my new email address, but from Ubisoft's side, with how the verification email is being sent.
Despite reaching out to Ubisoft's support team by email, I haven't received any response so far. Not being able to update contact information critical to my account's security and access is causing me serious hardship and putting my account at risk.
I am requesting the necessary technical review to ensure the verification code is delivered to my new email address, that the email change process be carried out manually on your end if possible, and that I receive written information regarding the process.