when you use collapse transformation on a pre-comp and apply a mask, effect or use the pre-comp as an alpha matte,
or apply a layer style - you lose the ability to have the insides of that pre-comp interact with the correct composition (blending modes for instance).
what you are left with is only the collapsed transformations (you can scale, rotate with preserving the original pre-comped resolution)
it's not a bug - its a compromise you have to work around with.