Muscovies do take longer- but the OP mentioned in a post elsewhere that they dont have any.
Also- Just as a thought- although I havent kept calls myself- I do recall reading that many people do have issues with calls hatching. Something about them needing assistance at times because of the...
There is two issues I see as most likely contributing to them not having hatched yet at day 29. Either the temp in the bator was a bit low- or the humidity was too low and the membranes have dried out too much and they cant move inside the egg.
If it was the temp- they may still hatch but just...