Hi, save states break upon certain Citra updates as well as on repeated use (saving upon save state loaded progress repeatedly). Thus, they are only recommended to be used within single gaming sessions, and not beyond them. You should use your in-game save files most of all for recording your progress.
Now, if you haven’t saved in-game at all up until this point, you’ll need to use an older Citra build to load your save state, and then save in-game. If you don’t know which Citra build that was, I can help you find out using a log file. Please upload one.
^ This one is incomplete. Make sure you follow the steps carefully:
Open Citra, then go to File>Open Citra Folder (Citra>Open Citra Folder if on MacOS) and open up the log folder. Now keep that open in the background.
Launch your game and encounter the problem; crash/slowdown/glitch and close Citra if it doesn’t do so by itself. Do not restart Citra as that will wipe the log of important information!