From what I can tell, CMS seems to be struggling with the newer System Chassis types like 31 - Convertible outlined in SMBIOS 3.0. I should be able to limp along with a Custom Inventory, but are there any plans to include them in say 8.7.3?
If anyone needs, I found them all here with their hex codes (PDF warning).
Pulling it off a computer is literally just (get-wmiObject -Class Win32_SystemEnclosure -property chassistypes).ChassisTypes in PowerShell if anyone else want to do a Custom Inventory in the meantime.