Well, they released a trailer with actual footage, but that bombed and has become known as the “worst trailer in the history of the internet”.
Feig tried to handwave that away by claiming that since they were still working on the special fx, they couldn’t put the best shots in the trailer. Thing is, this is supposed to be a comedy. If the only good shots are special fx shots, then it’s obviously a failure as a comedy.
But also sometimes the funnier a trailer is, the worse the movie, because it usually winds up being the only funny parts of the movie.