Personalization rules are under attached to the rule "Conditional Renderings". Here is the path to follow looking for your missing rule.
Tags
A tag is the glue between rules and elements. You will have a custom tag under the item, /sitecore/system/Settings/Rules/Definitions/Tags/
. Lets say that are called Membership Status
. i.e /sitecore/system/Settings/Rules/Definitions/Tags/Membership Status
Element
Under the item path /sitecore/system/Settings/Rules/Definitions/Elements
you should have a Element where you custom rules exist. You will create a new element called Membership Status
. In that Element there is a Tags
item and a child called Default
. Path would be /sitecore/system/Settings/Rules/Definitions/Elements/Membership Status/Tags/Default
. In the Tag multilist, in the custom tag, you select the Tag you created in step 1 above.
Condition Renderings
Finally you will have a custom Tag under the item /sitecore/system/Settings/Rules/Conditional Renderings/Tags
. I usually name the tag custom. In the multilist, in the custom tag, you select the Tag you created in step 1 above.
Your rules in your Element Membership Status and tied to the rule Condition Renderings via the Tag Membership Status.