Siri used to calculate BMI, but now has difficulty . . .

I use Siri regularly to quickly calculate BMI (body mass index) for patients. I generally phrase the question like this: "Hey Siri calculate the BMI of a person with a height of x feet y inches and a weight of z pounds." This phrasing would routinely yield a display from Wolfram Alpha containing the requested answer. Now such phrasing only leads to a web search, which would take me to a BMI calculator, but then I'd have to input the data again. I don't want to do that. Even directing Siri to use Wolfram Alpha to perform the calculation, she returns a result "I don't find that on Wolfram Alpha." Is Siri getting stupider or is there something I'm missing?