When you create a rule using a custom condition or action and then change the namespace or the name of the class. You are no longer able to edit or delete the rule. I think at least the delete operation should be possible. This forces developers to keep legacy/obsolete code in the codebase untill old rules are deleted on all environments.
This is possible with the commandline tool, so why not fix it in the UI?
FYI see support request #9798
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