Are they really gone, or did you have to wait a real long time for them to show up. iStripper is a little over paranoid when it comes to Mac updates. Every first time after a Mac update I always have to login to iStripper again. Did you have to do that as well and did you use the correct account to log in to iStripper?
In the last couple of builds it also sometimes takes a real long time to start up where you can see the spinning icon in the menu bar as if it is rebuilding the collection, but the app continues to start up and you can use it. Your collection is not there until the icon stops spinning. Does that match your findings?