"Modern" ARC Rules suffer from many many problems associated with their deployment, activation and management - particularly if you have more than a handful in multiple environments.

Please consider enabling them for audit so that users have some chance of figuring out how/when/who caused one to stop working. At the moment auditing cannot be enabled and so it is impossible to see who/what/when ARC Rule configuration (and indeed Rule Item, Rule Flow, Rule Item Flow configuration) was changed.