Not recognizing Jesus. That's on us. This is not something God would intentionally do, right? But here, in the story of two travelers heading home to Emmaus, it's true. God blocks their understanding, at least for awhile.
We think God's job is to promote His Son, His beloved, with whom He is well pleased. To withhold info? That doesn't seem right.
But God does it.
God does it because sometimes we have to travel longer with Jesus being a stranger to us to realize with such a greater impact EXACTLY who He is and EXACTLY where He has been (which is beside us the whole time). The "Aha!" moment would have been great within the first moment of seeing Jesus as Jesus, the one crucified and now alive, but these two have forever been impacted by the metaphorical road of life with Jesus, their literal walking companion.
Rather than an "all at once" for all of us, Jesus continually opens the scripture for us, one beautiful step at a time.