Having the same problem. I've been thinking to remove all LPS and getting a fish that will eat them. The only problem is that it is hit or miss if they will eat the mushrooms. I'm hoping I will run across some one that has one that is looking to get rid of.
I always have issues getting mushrooms to open fully and multiply. Why? My lighting is too intense for mushrooms. They like lower intensity lighting so more light will suppress their growth.