As Luke Sawczak said, the Hebrew phrase there implies no one understood it -
including Daniel himself.
And I, Daniel, have been, yea, I became sick for days, and I rise, and do the king's work, and am astonished at the appearance, and there is none understanding.
Daniel recorded a similar situation in chapter 12.
And I have heard, and I do not understand, and I say, 'O my lord, what is the latter end of these?'
And he saith, 'Go, Daniel; for hidden and sealed are the things till the time of the end;
He says that he did not understand the vision and that was by design. Daniel is not talking about chapter 8 in chapter 12, but the fact he says he himself did not understand in chapter 12 leads me to think he meant he himself did not understand in chapter 8. If he understood the vision he could have just explained it to others like he explained the metal statue in Daniel 2.