The standard behavior of Sales by Promotion Report only generates the Invoice and Cash Sale transactions. The report does not include data from transactions that have stackable Promotions. When the SuitePromotions is enabled, it will not display any results because the transaction form assumes that stackable SuitePromotions is applied. To override this behavior, disable the SuitePromotions feature.
Note: The Sales by Promotions report displays the Invoice and Cash transactions created after disabling the SuitePromotions feature. Disabling the feature is not retroactive and it will not generate the transactions created before disabling the SuitePromotions feature. Use the Sales Order by Promotion report to generate the Sales Order transactions respectively.