I have used FP on MANY jobs and it is my "go to" grout. Yes, there is a learning curve to it. You can only grout small areas at one time and you need to use VERY little water to clean up...and a microfibre cloth for the final haze. It is imperative that, particularly in a shower or "wet" area you honor the "7 days with NO water" edict. If you do that, you should have no problem......
Q
Lacava 35” undermount sink
Q