In Sitecore XP 9.0, several of the new stored procedures are not present in the DACPAC for Azure for the Marketing Automation database. As a side effect, high CPU consumption by the Marketing Automation (maengine.exe) service can be observed.
After allowing client IP address in the Azure SQL firewall, connect to the Marketing Automation database using SQL Server Management Studio and create the following stored procedures : AutomationPool_Stall ContactWorkerAffinity_ReleaseLease ContactWorkerAffinity_TakeLease and the following table: StalledAutomationPool by executing the UpdateMarketingAutomation.sql script.