The bidding rule will not change keyword bids under the following conditions:
Condition #1: The bidding rule adjusts bids based on Target ACOS.
Condition #2: The keywords did not generate any sales.
If a keyword has generated sales, the algorithm can compute optimal bids based on revenue per click * Target ACOS.
We do not have the logic to compute optimal bids without sales when the HSA campaign consists of 3 products with different conversion rates and possibly different selling prices.
To cater to HSA keywords without sales, you need to supply the logic to adjust the keyword bid based on different criteria.
For example, if a keyword has >= 15 clicks and 0 orders, reduce the bid by 10%.
Another approach you can apply is setting the minimum and maximum bid to the amount you are willing to pay.
This is based on the profit margin of your product, not on your current CPC that aggregates value across multiple periods.
This way, you would have absolute control over how much you're willing to spend based on the performance.
For example:
If a keyword has 5 to 10 clicks with 0 orders, set the minimum bid to $0.50 and the maximum bid to $0.50.
If a keyword has 11 to 15 clicks with 0 orders, set the minimum bid to $0.40 and the maximum bid to $0.40.
If a keyword has 15 to 20 clicks with 0 orders, set the minimum bid to $0.20 and the maximum bid to $0.20.
Once you have made the changes, remember to preview the rules to verify the algorithm will adjust keyword bids without sales.
Consideration #3: The campaign/ ad group is not active.
For the automation rules to apply, the campaign and ad group must be active unless the Dayparting rule pauses them.