I however downloaded the updates of November 11st and 15th to solve this problem. But without success, it is still impossible to leave the gate because although the brake is released, the ramp agent keeps asking me to release the brake.
Assuming your report is correct, and it's asking to "release the parking brake", exactly as written, it indicates you haven't installed the update because, after the update, it's supposed to say "release Parking Brakes or Chocks", which indicates the airplane has been recognized.
are you sure that this patch has been integrated into the updates of these dates ?
Of course it has.
What is the solution ?
Check if you haven't made a custom profile BEFORE the airplane was internally supported. Custom profiles always take precedence over the internal ones, but when special features like non-standard brakes are added, you need to wait for the internal support before you can customized it.
Note that this is not necessarily valid anymore, since in a recent update, we added the ability to edit the custom parking brake expression too but, again, if you made a profile before that update, you need to remove your custom profile, so GSX will use the internal one.