3 at the back Centerbacks marking AI seems completely wrong in Ultimate team

Hi

I know this is a really long shot. But I gotta try to revive my beloved 3-5-2. As I try to play this formation in this years iteration I’ve come across something that’s highly frustrating. As I have a back 3 the left and right CB drift out towards the sidelines when the opposition has the ball. Just no logic in the position/poor marking. Inviting for attacks on the inside. They also don’t seem to understand marking as they just stand at the top and bottom edge of the box while pushed back, according to which side they’re on. I’ve tried having CDMs on half winger and LM/RM on defensive yet it continues to happen. Their marking is just non existent. The drift is worse the higher press you’re on. This was fixable in previous years with the width slider to force them more towards the center. And by doing so closing the gaps but giving up more space wide.
CBs feel like they mark much tighter while in a pair in a 4 back.

If this is a feature could you please let me know so I can lay my hopes of getting the formation to work to rest. Please also add an explanation of why they should behave like that 

if it’s not a feature I beg you fix it so my formation can be revived

Regards

Long time FIFA player