I’m looking at Chaggai 2:12.
It seems that G-d decided that his questions to the Kohanim should be recorded for posterity. Why did G-d not make the question clear and tell them (or us) if the Kohanim answered correctly?
On Pesachim 16/17 Rav and Shmuel disagree about what exactly was asked and whether the Kohanim answered correctly.
What you are asking can really be asked in another thousand places in the written torah. Wherever we look in the written torah we find that there are pieces missing and there is a need for explanation. The question is why did G-d do this? One of the answers is, that G-d specifically wants that we should have to come on to the oral torah, and that torah should essentially be transmitted orally. This keeps the true explanation of the sacred torah hidden somewhat among the Jews.