Error reading BMI: Attempt to convert incompatible units: count, kg/m^2

I have code that's been in production for a year and never had any issues reading BMI. One of my users just submitted a bug report saying that attempting to read BMI data crashed the app. The error Xcode shows is 'Attempt to convert incompatible units: count, kg/m^2'. Now I'm pretty sure the unit for BMI shouldn't be "count" so what the heck is going on? Is this a bug? This is happening on watchOS 9.5.2.

Please note that this app version was released to the App Store a year ago and worked at that time (and presumable until recently).