Looks like you've got conflicting events..
When the conditions of an event are true - the actions will be executed
when the conditions of more than one event are true - all the actions of those events are executed
so if you have
on up key pressed - set animation up
on left key pressed - set animation left
on up key pressed and on left key pressed - set animation upleft
All three of these events will run when up and left key are pressed at the same time..
so every tick the animation is first set to up, then to left and then to upleft
in effect it will look like the animation freezes..
Adding more conditions will prevent the conditions of all three events to be true at the same time..
One solution (albeit not the best) would be:
If up key is pressed and left key is not pressed - play animation up