I'm curious about this as it never happened to me and Bulbapedia said it has a hundred accuracy. Does the rng hate me or does it actually always land?
If Future Sight misses, the miss will not occur until the third turn, and the game will display that the move "failed" rather than "missed".
Source
Therefore, it can miss normally due to Sand Veil, but it shows "failed" rather than missed.
Hope this helps!