why almost all of my players have 0 (zero) morale!! ??
Even the players who play most of the games and are never substitutes have a zero morale! What a Bug! :clapwap:

Why this happens? and is there a way to fix it so it ll be more realistic?

Morale, from my experience can also dip if players start winning every single match and their energy levels stay high. It can also drop if their contracts are close to finishing or if they want a higher salary. Just increase the salary by a notch and the morale will return. Change formation regularly to see which players work best and thee should be an overall change after you do these things