I too have been having the same problem with the black box appearing. It's not always a black square, . . sometimes it's a black rectangle. It depends on the add. There is no way to tell WGT which add it is, because it's just a blacked out area where the add was suppose to be.
What I'm finding is if the add does not completely configure on your monitor, then the black box will appear in it's place. Seems to me this all started when WGT changed the add format when showing the score card. The score card got smaller with adds on top of card and below it. When one of those does not configure on your screen, then when you go to next hole, you're left with this black rectangle.
Could not play AS game, because of this bug yesterday. Tried closing out and coming back, but could not get rid of the black space. So I had other golfers telling me to change my browser which is total BS, and does not solve the bug.
Today while playing in CC tourney the black box started again on the back nine of an 18 hole round. Had to close out numerous times to get the game completed.
Next time it happens I will try some of the fixes that others have said might work, but I will not change browsers, because that's not the problem.
Thanks.......