Inversion works because the obvious question and its opposite draw on different information. Your team has usually spent a long time on the question everyone asks first, and by then it has stopped producing new answers. The opposite question has had far less attention, so it still has something in it.
This shows up in meetings as a brainstorm that stalls on one question and starts moving the moment you flip it. A session that has produced nothing new on "why didn't the other 20 accounts buy" can change direction fast once someone asks "what did the 5 that bought have in common". The first question hunts for what went wrong, and the second finds what already works.
Inversion also helps with indecision. When every forward option looks equally uncertain, ask what would make each one fail and you have something to compare: the option with the fewest ways to fail.
The practical tell is a brainstorm that has produced nothing new in the last few minutes. That is usually the moment to ask the opposite question instead of pushing harder on the same one. Write the answers down, then check your current plan against each one.
After the first month of a new-business push, 25 accounts had opened but only 5 had placed an order, nowhere near enough to reach our £1,000,000 target. We worked through ideas, a first-order discount and a new welcome pack among them, and I still felt we were missing something. The answer came to me in the shower: we had spent the meeting asking why the 20 hadn't ordered and never why the 5 had. Every one of the 5 had been visited by a sales rep within a week of opening the account, and that window, our "golden hour", became the whole fix, with no discount and no new welcome pack.