Everything will be okay in 8 bit mode. However, when using 16 bit mode, importing psd into the AI and ID, if there is a group of layers inside a transparent background PSD (no solid colour there), group with layer mask will not work properly, especially the opacity function of those layers inside the group. Without layer mask or not, the opacity of the layers inside the group is totally different. It seems, the calculation of the opacity getting error when there is layer mask even it is white with nothing!
I got more detail now: if a group of layers only contains some adjustment layers like solid colour, etc, the problem happens.