The error message they receive when trying to do so reads, “Something’s not right. Try again a little bit. (8000ffff).” Apparently even soft or hard resetting their phone does not seem to solve the issue either. There is also the possibility that it might be because Cortana is being used in another country other than the US, but there are US users who are reporting on the issue as well.
However we should note that as it stands, Windows Phone 8.1 has been released as a Developer Preview meaning that it is not primed for use for end-users just yet, although we would have expected Cortana to be able to set alarms since it’s a pretty basic function. Hopefully this is an issue Microsoft will look into an issue a fix if necessary.
In the meantime any of our readers running the Windows Phone 8.1 Developer Preview on their Windows Phone handsets run into the same problems as well? Do let us know in the comments below, especially if you’ve figured out how to make it work!