I came across this while debugging #4889. This does not actually fix it, but it fixes an inconsistence in the casing of the parameter name.
However, I think the original issue is a caching problem in the browser. I was able to reproduce it on first load, after reloading the page once more it works as intended. The weird thing is: even though the values are correct on first load (verified via debugger), the `choiceKey` for the first item is set incorrectly to an integer value.
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