Yseribus,
Did you really just claim that no messianic movement ever started ever continued to claim someone was moshiach after he died?? Thats not in the slightest true. It’s in fact a reoccuring phenomena and has occured throughout the ages. As a reminder, it is not a good attribute to talk on things u have not done any reading on, its a disservice to those reading your comments and to yourself.
Very famously this happened with Shabtai tzvi. The Rambam likewise mentions people who believed their moshiach would return. followers of David Alroy likewise continued after his death. The list goes on.