The question didn't exist yet
Some questions don't get missed in refinement. They only become possible once the work begins.
Some refinement meetings are almost too easy. The requirement sounds clear, the ticket is accepted, and nobody has many questions.
Then implementation begins.
A field needs a default. Two rules compete for the same behaviour. An API response that sounded obvious in conversation now requires a precise shape.
It is tempting to blame the meeting. Someone should have asked earlier.
But the same pattern appears across different teams and features. The questions arrive when an idea must become an exact thing.
Building forces choices that a description can leave comfortably unresolved.
Refinement should expose the questions that already exist. It cannot always produce the questions that only become possible through contact with the work.
The answer is not to make every meeting longer. It is to keep discovery open after the meeting ends—and to treat new implementation questions as evidence, not failure.