Error 60674 when editing a Shared Distribution List

[FHLBSteve]

I have an existing Static shared distribution list (3 digits in length) with thirty entries. When I open the list and save it I get an Error 60674 - " Address conflicts with a long distance prefix." doesn't matter whether I edit or not. The list works currently as is but I need to add an entry.

I can create and save a new list just fine. provided I use four digits. Not sure what has changed.

NPA and NXX do not exist for the SDL entry I'm working with

Version, Call Pilot 5.0