From what I can tell, it looks like SmartThings pushed a device type handler update for switches tonight which broke the Things list parsing in SharpTools. I’ve reported it to the SmartThings developer advocacy team and I’m pushing a hotfix for SharpTools tonight (2.2 R4) to work around the issue.
It looks like switches have dropped the unit attribute from the list of currentStates which SharpTools was explicitly looking for. I’ve added a workaround which provides a default empty unit if the unit attribute is missing.