Try putting the rule on the @Product_Estimated_Sell_Amt. For example,
Condition: When @Product_Estimated_Sell_Amt > 0
Action: Set fields value: @ActualThirdPartyBudget = @Product_Estimated_Sell_Amt
This way the field @ActualThirdPartyBudget will always change as long as the @Product_Estimated_Sell_Amt value is more than 0.
What
I have found is that if you put the rule on the field you want to
change, even if it is set to run all the time, it doesn't fire. It
needs an event for the rule to fire.
Hope this helps. Let us know.