CF rank points. question!

hello everyone.
just interesting.
i had 4500/5000 points last season.
i have completed it on legendary rank this season, so i got 2000 points.
4500+2000=6500.
i have purchased C4. (5000 points right?)
but i have 0 points now. where is additional 1500 points?
it is not transferablle or it is just bug?