since 26c Standard Annual Working Duration field is missing from New Position screen

Summary: Since 26c went in - on the New Position screen > Standard Annual Working Duration field is missing from the screen. This is a mandatory field. Without population, this creates an error due to Validation of annual working duration (brought in as part of mandatory 24D functionality).

Triggers error: "You need to either enter both the standard annual working duration and the annual working duration unit, or leave both blank for position code.(PER.1532833)"

Advised by our SI that the workaround is to make the field visible by VBS. However, does anyone know what caused this issue?

From research, is it to do with complications around the new optional feature Manage Positions with AI assistance?