Ever since we upgraded to Lookup Editor 4.0.1, any KVstore changes made in the app don't save for some reason. It says they do, but they don't. CSV files work normally.
Hey - we've ran into some weird issues with the new Lookup Editor app before and it isn't the same issue you're having, but can you try to clear out your browser cache and history to see if it fixes your issue?
This is being experienced by multiple users, so a browser cache isn't the issue.