I'm having a similar problem with rendering glass that has Voronoi fracturing. Simply put when I render with Mantra with just the Cd it renders fine and the cracks don't show up pre sim. However, when I add a PBR Glass shader all the cracks show up from the very beginning. I've attempted doing a lot of fixes over the past few days but I cannot get it work. The sim itself is still a work in progress, but I wanted to make sure first that the Materials are working properly (had this problem before). I attached the hip file also.
Wondering if anyone could lend me a hand, that would be awesome!