Ok if you want an explanation, basically Castle taxes the bricks you recieve from snapshots, they take at least 20% of the bricks, which means:
50 bricks snapshot → 40 bricks you recieve
10 bricks snapshot → 8 bricks you recieve
And so on.
But, when the 20% isn't a whole number (when it has decimals), Castle takes the ceiling of the number, like:
6 bricks snapshot → 4 bricks you recieve
3 bricks snapshot → 2 bricks you recieve
When the snapshot bricks are 1, Castle takes the ceiling of the (20% of 1 (0.2)) which is 1, so Castle takes the whole 1 brick and gives you nothing.
I hope someone understands this.