If the custom profile fields values can be displayed in the memberlist (depending on the settings of the customs profile fields in the ACP), their legends are sometimes hidden, or only the legends of specified custom profile fields are shown.

The bug doesn't appears when you view all user groups (default memberlist page) but it does when you view an user group.

See the screenshots attached to that message. The test board has two registered users (the first with empty custom profile fields, the second with a specified Location, Facebook and Website.