Auto Complete rule triggers at Salary Section when Assignment Category Changes

Hi

We had a custom auto complete rule for Object Validation at Worker Assignment section, Basically this rule will check if the default FTE when working hours changes and pop-up an message based on some calculation, We observed the rule was working fine when we changes the Working Hours directly on Assignment page and on clicking continue it triggered the validation message but the same transaction when we change the Assignment Category before or after the working hours field the rule is not triggering on the Assignment Section and it triggers on the Salary Section and not allowing to go back