Mail Rules Not Working

A client had an issue where one or two of his mail rules in Notes 8.5 (Notes 8 template, Domino 8.0.1 server) stopped working. He played around several times with disabling rules, deleting them, etc. We even disabled & deleted all his rules, ran some script to recompile his rules, and I even deleted the calendar profile. When he re-created 2 of the rules, still no luck. Then I looked more closely at the 2 rules he had re-created. To my surprise, the OrderNum fields of the 2 rules were numbered "1" and "3"....but no "2". On a whim, I decided to use my "Edit Any Field" SmartIcon to change that "3" to a "2". Surprise, surprise: after that, the rules worked fine! I'm not sure if Notes was seeing a rule numbered "2" that was disabled, and therefore was not applying the other rules, or what. All I know is it seems to be fixed!