The next release (1.6.0) will be available for download in a few weeks. It contains a dedicated CM86 adapter to utilize new features. In the meantime, you can make a connection with another adapter by using the 'Force' parameter:
PS > $cm = Connect-CM 10.0.0.1 ucmadmin ciscocisco cm85 -Force
This way CMShell communicates using CM85 AXL schema, regardless of the actual CUCM version. Please refer to Cisco documentation for details on AXL versioning and compatibility.