In Custom Pages, used to embed a light canvas app inside a model driven app, the combo box is limited to 500 rows. Updating the data limits in settings to 2000 does not allow the user to increase this limit. However a Gallery will load up to 2000 rows. Users should be able to have the combo box load 2000 records if needed. Understood it is a performance hit, but let the user decide if they are willing to trade performance to build the app the user needs. AND update the documentation for Custom Page controls as they DO NOT work the same as the same control in a canvas app.