[Unexpected behavior] Setting box constraints on some input i

[HatsuneMK00]

Hello!
When I am trying to set some box constraints on part of input I using DSL, the result is not what I expected to have.
DSL is like the following:

FIND i[10]
S.T. i[5:] in [1, 2],
...
RETURN i

I am expecting that last 5 items of i is restricted in [1, 2], but the constraints don't seem to work in the result.

The similar thing happens when I use mask instead of slice operation.
DSL is like the following:

FIND i[10]
S.T. i[mask] in [1, 2],
...
RETURN i

The mask is like 0000000001(only the last one is true), but in the result, seems like the first element in i is restricted by the box constraint.

I'm wondering if I have some misunderstanding about the effect of DSL above? Any advice would be appreciated!