Quest \"The Assault On Fort Independence (Fallout 4)

Play is not the first time, and because of this, I immediately went the way of the Minutemen, and went to subway, met a couple of quests and during this time managed to open the floor map and clean up this damn Fort without the quest, then decided to go a bit line of the Minutemen and found that after taking this quest from Preston Garvey and the start of the assault the Fort itself cleaned but the fourth task Clean up the yard simply fails, What to do if you've already played 13 hours of gameplay, and I cleared it for 3 hour survival in the wasteland around XD? And please do not write something on the type otchityvatsya to 10h for the saves, I BEG of YOU!!!