Can't use High Memory Instance because vCPU limit

Hello! I need to use a High Memory instance, for example u-3tb1.56xlarge (which uses 229 vCPUs). However, when I tried to launch the instance it gives the following error: "You have requested more vCPU capacity than your current vCPU limit of 0 allows for the instance bucket that the specified instance type belongs to. Please visit http://aws.amazon.com/contact-us/ec2-request to request an adjustment to this limit." I've done the request for vCPU upgrade, and it was confirmed by support that the new limit is 250 vCPUs. However, it still doesnt work (I have checked the region and the instance and vCPU limit request was done in the same region). Then, when I check the page "http://aws.amazon.com/contact-us/ec2-request", I noticed there is a drop list, and "U" instances are not listed (when I did the request, I choose "All X instances" ) Does someone know what could be the problem and what should I do?