Users no longer able to see rule but rule security was not changed

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Hello.

We have a continual issue where our user security on business rule changes unexpectedly. I realized that if I changed a rule NAME it would remove all users, so I would have to add them back. However, I now a user saying he cannot see a ruleset, although he has permission for all rules included in the set, and there were no name changes.

What is the rule/policy/process around rules security and changes? I want to find a way to make updates as needed without having to revisit access each time.