recurring tasks not showing completed on iphone

I’m new to em client and so far very impressed. I am setting up em client on 30 day trial, all is good so far. I am syncing em client on pc to iphone via icloud email and it all seems good except a recurring task, when I set it to completed on em client it does not show completed on iphone but it does the other way around. This does not happen on one off tasks, only recurring. I’ve searched the forum but no luck, any help appreciated thanks