Behavior is different between the ArcMap based Service Area solver properties in ArcMap and the Make Service Area Layer GP tool. When setting break values in the GP tool, values seperated by a comma and no space will default to an unbroken series of numbers. When setting break values in ArcMap (via a service area layer properties) break values will autopopulate spaces if commas are present. There should be consistancy between these tools. The easy solution might be to throw an error in the tool when commas are used. Whatever the solution is, a user should not be allowed to provide invalid input.
When running the gp tool the break value will be 66013202640. This is an unexpected outcome:
The arcmap tool will format a spaceless string if a comma is present. Image on left is the initial entry. Image on right is the result when opening the properties window imeadiately after the initial entry. Notice the spaces. Why would setting the properties in this way result in a defaulted comma/space format? What is required according to help documentation is a single space delimiter. It doesent appear that the software behaves in a way that is requested in the help document.
" ... specify "2 3 5" as the value for the Default break values parameter (the numbers 2, 3, and 5 should be separated by a space)."