There are some issues with tackling atm. Both standing and slides.
You can be pixel perfect on a tackle and it wont connect. Me and my friends have gone over replays after games, frame by frame, and see feet literally going through the ball but not connecting as a tackle.
There are also people phasing through you center mass, even though you are standing in defensive stance.
You need to look into this, because it's clearly not what is intended. Tackles should connect when they connect. No real discussion for that.