Odd situation came up on MTGO, and I got a reimbursement, but I wanted to make sure the reimbursement was correct and that I understand the interaction.

Opponent has a Dauthi Voidwalker in play and I have a Leyline of the Void in play. I cast Gyruda, Doom of Depths. MTGO pops out menus to show your options of which milled cards to select, but I only had the option of the opponent's milled cards. When I watched a replay, it showed my milled cards going into exile with void counters on them, but not highlighted for Gyruda purposes.

Voidwalker works the same way as Leyline, and I should have had the choice of my milled cards too, right?