The elephant in the room
Sharing information and opinions can at times fall prey to group think or other forms of conformism. That can prove dangerous. Important information can be overlooked. It may be that is is known but not easy to mention. It could also be hidden in plain view.
Talking about the unsaid
One way to deal with this, provided you are in a company that can stomach this kind of question, is to ask “what is the elephant in the room?”. Then listen either to the silence, which means the elephant is coming soon in all its splendor, or to an immediate reaction, most often denial, which mean the pachyderm is trying to escape the conversation. Keep at it. hopefully some inquisitive mind will join you in the conversation. One last bit of information: the elephant you get may not be the one you sought.