Quick update:
KBA 2060375 has just been published: http://service.sap.com/sap/support/notes/2060375
It references Sybase bug 769919 which was fixed by engineering and currently under Q&A.
Once I know the PB 12.6 build number, I will update the thread.
P.S.: Christopher, if you have a use case example, I'll be glad to test it once I got the fix.
Jacob