I’m having some problems with this too. I’m currently trying to purify a large section of my world, and crimson keeps reappearing in different places. Some of this is just me missing spots while using the clentaminator, but other times my friends see crimson that isnt there on my screen. I started doing most of the purification in singleplayer which seemed to mostly fix the issue, but its still annoying if you want to purify with the help of other people.