Bad epoxy grout install or terrible cleaner?

I hired a highly-rated tile company to install new porcelain tile in my master bath. The specifications called for epoxy grout. It’s approximately 5 months old and I’m getting terrible mildew growth. We use an exhaust fan, liquid soaps and squeegee 50% of the time. I clean with a bleach based cleaner once a month. These pictures are taken after I cleaned. There is a sandy substance coming out of the grout line, which is very rough textured and changes color when wet. Am I a terrible cleaner or did I get a bad install?