Is there any good reason why you have to use Collapse Transformations / Continuously Rasterize switch on that layer?
As Dave was hinting at, it behaves as expected. Using collapse transformations/ continuously rasterize passes through blending operations from the pre-comp when not used with 3D layers. This is a fundamental feature of this stuff that 99.5 percent of users are completely ignorant of. Don't use CR or restructure your pre-comp. I guess you have learned something today?!