Messages not Syncing Across Devices

I have tried all the advice from Apple support to get messages to sync across all my Apple devices more than once. Shut everything down and then logged back into iCloud. No change. Messages deleted on iphone don't delete on Mac or ipad. Message deleted on Mac still appears on iphone. This used to be so easy and automatic and now it is not happening. Since there is no way to select multiple messages for deletion on my Mac it is a real chore to keep it cleaned up. It looks like only solution is to turn off Messages on all devices except for my iphone and just work from that.