HI @Syphe ,
A similar happened to me, and I am UK-based. The emails were getting sent to the spam folder, and incorrect filing in the Tax form resulted in infinite delay.
Have you followed the directions in
Set up your Tax Profile and Hyperwallet account - Creator Programs Support
The first time around failed to read, being a developer who RTFM 
if you are an indie dev then you must enter your personal tax number, this is country specific
not the number of the sub-contract shell company
Sadly you might have to wait the 30 days and start again if you cannot find the error.
You only have 3 days for tax information after that the Tax Amendment locks.
This is NOT Epic fault but a IRS/HMRC tax control.