There is a thread here on Schlage Z-Wave locks having problems since the last update a months ago. One user got a message back from SmartThings support that they applied a vendor patch from Silicon Labs and that broke the Schlage lock, but it was somehow Schlage’s fault for doing something incorrectly.
If I had to guess, that patch broke communication with other Z-Wave devices as well.
I suggest contacting SmartThings support and pushing hard for a fix to the Z-Wave problem they have created.