We have added the Charge Code correctly at Project Level and Task level. The Charge Code is not added as field to Timesheets so the users do not set it up.
We noticed transactions were Rejected due to "Missing or Invalid Charge code". Why was this?
Release : All Supported Clarity releases
Component : CA PPM SAAS FINANCIAL MANAGEMENT
Most likely the charge code was set on project/task level before the timesheet was posted. Then even if the charge code was changed, it was already recorded.
You can also try to Open and Populate a new timesheet for this resource and same project and task, with the Charge Code field in the Timesheet. You will then see which Charge code is added by default.