After upgrading from 15.6.1 to 15.8.1, the Sort Order of OOTB static lookups is changed from Alphanumeric to Manual.
Lookups impacted below:
Is it possible to revert the Sort Order?
For example, see "Assignment Pool" on Project->Properties->Settings.
In 15.6.1, the Sort Order of Assignment Pool is Resource Pool -> Team Only.
In 15.7 or higher, the Sort Order of Assignment Pool is Team Only -> Resource Pool.
In Administration -> Lookups, you also see the sort is set to Alphanumeric prior to 15.7
15.7 or higher the Sort Order is now showing as Manual:
Release : 15.7 and higher
Component : Clarity Studio
The Sort Order of some OOTB lookups was changed as per design to Manual in 15.7.0. Prior to 15.7, it is defined as Alphanumeric.
The reason it was made it 'Manual', is so that the administrator can re-order the values on the OOTB static looks for all users to see the columns on the Boards in a specific order. This affects the order in the lookup pull-down.
It's not possible to change the Sort order type for these lookups, the only option would be to change the values manually from the Reorder Values tab on the Lookup
Screen shot below.