Character Movement in C++

I am a noob,
Can’t seem to figure out why my character moves at different speeds at different angles, I am using a simple 1d blend space for idle, walk and sprint.
When I move my character it walks while vector magnitude is 300 but when I turn it to a certain angle it slows down(animation too) to 243.f.
I saw the same behaviour with default mannequin in the third person template I guess.
Please Help me!