It is a common requirement that every business may have its own business field level information over and above the standard Resource fields to allow searching for the appropriate resource for a particular requirement.

However, these custom field values in form of lookup to another custom entity cannot be sorted. For OOB entities I believe standard sort attribute can be used but for custom fields, sorting is not working. Its is not a very good user experience to scroll through a random list of values. Thankfully search works but values cannot be sorted alphabetically.