Altium Designer PCB project Ground fill polygon cant connect to one of same net component pad
It looks like you have the polygon connect style set to relief connection at 45 degree angles. But this pad doesn't have enough clearance around it at the corners to make a connection at 45 degree angles. 

Try changing the relief style in design rules, under the "Plane" cateory, to relief connection at 90 degree angle. 

If you don't want to affect the rest of your design, you can make a new rule for this named polygon only, to change its relief style.