If not bands are selected Multilook will apply to all real and imaginary bands and copy over all virtual bands. Phase band will not be mulitlooked but a virtual phase band of the multilooked i and q will give the correct histogram

For multi-looking interferogram, one should multi-look the complex interferogram and should not multi-look the interferometric phase only. The correct way is to muti-look the i/q bands first, then compute phase as virtual band from the multi-looked i/q bands.