Multi-nested, multi-block mixins in lessphp

Question

While transforming some code to lessphp from the classic less code; an incompatibility I discovered from the classic less css is that there is no support for multi-block mixins with nesting levels > 2. The classic less seems to be fully in support of mixins having many nested blocks in them.

Is this intentional - the support for just two nesting levels inside mixings?

Example:

 @some_mixin{
  height: 22px;
    ul{
    height: 20px;
    li{
    height: 10px;
    }
    }
 }

what happens above with lessphp is that the third nesting level; which contains css code for the li tag is totally ignored!