I can imagine that some of the complicity started with benign motives. You’re an NGO wanting to do good things for the people of Gaza? You learn and obey Hamas rules. But since you don’t want to admit that you are obeying Hamas rules - you get drawn into endorsing Hamas lies. Nonetheless, by not saying anything about the hostages for a month you are complicate in their capture and your organization is as well.
Then there are those that doubt the veracity of Israeli and US Intelligence saying that the hospital was a control point. Of course it was, and those that watched Hamas walk into the door knew it.