The user table is no longer held in your datasource, this is now located within Stacker.
To be able to apply "Can access record only if" rule to the permissions table, there needs to be a way to connect the Stacker user table to the data source, we do this with user profiles.
For example if we wanted to use a particular permission rule in a given table, selecting "can only access record if" gives no options.
User profiles can now be used to create this link.
Go to App Settings and select this in the menu.
Select the table that you want to use.
In the example we will be matching users email with clients name.
Once set up, going back into permissions will now allow this as a permissions rule.