Same issue - I have multiple contacts in several of the organisations I invoice and this is so frustrating!
What's worse, in the old Essentails I just typed the contact name, so this feature has been removed! If it ever gets into the new version it won't be an "enhancement", just a return to the previous better version.
So far I have only found 1 thing that's better in the new Essentials and countless things that are worse or broken. It's almost impossible to believe how badly this change has been implemented.
Is there any timeline for this to be fixed?