Projects for Web - Incorrect Auto Calc of hours

On Projects for Web - When you enter a % complete, it automatically calculates the Effort Remaining. Conversely, if you change the hours completed and the Effort Remaining, it automatically calculates % complete. But... it's wrong. The Effort Remaining as a % of the total does not equal what it computes as the % complete. The % complete is what drives the hours on the Planner Cards though, and so, what shows on the planner card does not match the hours in the Effort Remaining box in the task details. This is causing confusion and we lack clarity of how the hours are being adjusted. Is there a bug? Or a Admin work around?