We recently changed some internal name data in regards to challenges.
(Example, renaming the Icy Companion challenge from "frosty" to "icycompanion" on the configuration side.)

Due to this, your challenges menu may look "broken" in rare circumstances.

To fix this, simply look through all the challenges once more and find what you are missing.
It is likely you will have to repeat one of the very early challenges again. After doing so your challenges menu will go back to normal and the issues will be resolved.

Sorry for any inconvenience.