My friend has the same issue. He didn't bother claiming items on the assumption that they will eventually be mailed to him or he'll be able to claim them before the next season and he didn't want to bother with inventory management. He has 100% of season achievements and didn't get a single reward other than the completion title and a few tokens. I don't know if CS will sort him out but if not then it will be grossly unfair. This needs to be looked at it.