We cannot change the Department OBS on the properties page of an investment.
Cause
This happens because once you enter a Department OBS the financial department also gets populated on the financial properties page. These two fields are essentially the same thing.
Defines the department that is used during transaction processing of chargebacks to charge or credit departments for costs. The department can also be used to match the project with Cost/Rate matrices. The field is auto-populated if a department is selected on the project general properties.
In the past it was possible to change the department OBS which caused the two departments to get out of sync and creating two entries in the prj_obj_association table for the department obs on the investment.
As a result of this, the financial properties page could not be opened as there was a duplicate.
This issue was fixed in 14.3 by making the department OBS not save when a change is made to it
Resolution
The correct way to update the department OBS is to do it on the financial settings page.
This way the two departments stay in Sync and the Location will also need to be reset as that also blanks out when the department is changed.