The App Store wish list is a section that each user tends to use it in a completely different way. In my particular case, I use it to add applications that I do not currently need but that I might need at some time, and as the App Store search engine continues to function in a quite improvable way, I have always preferred to have those applications on hand in instead of writing them down to me in some place or application that I will never ever remember. Other users instead use the wish list to see if the price of these applications is lowered over time to take advantage and download them.
For some time to be part, the operation of several of Apple's servers is leaving a lot to be desired and from time to time several of the services offered by the company stop working. Yesterday afternoon, Reddit was filled with new threads stating that a large number of users had seen how the wish list they had in the App Store had completely disappeared. Presumably or we want to assume that it is a specific error of the App Store servers, because it makes no sense for Apple to disable a function without prior notice so that users can make a copy or pass that information to another place.
If, unfortunately, you are one of the users like me and many other people affected by this incident and you cannot remember which applications you had saved in your wish list, it will be difficult to find out again what they were unless you remember what they were. We do not know if our desired applications will appear again in case it was a momentary failure of the App Store, but just in case, the best we can do is use third party applications like AppShopper or TouchArcade to point our applications to which we want to monitor or have proof, as is my case, which applications are the ones that I may ever need.
Apple servers they do not reflect that they have had any incidence in the App Store and those of Cupertino have not spoken on the matter either, so the only thing we can do is wait to see if they reappear or go looking for life as I have commented in the previous paragraph.
UPDATED: It seems that this problem is already solved and users are already being able to access their wish list again.