OK, great. I am glad you have a workaround. However, it also works for me in 2022R1 so I can't be sure that upgrading would resolve your issue. No matter what I try, I cannot reproduce what you are seeing. "mut" is a predefined variable so maybe your compiler is doing something strange there. You could try renaming it to udf_mut. If that doesn't work then it would require a deeper investigation that we cannot provide through the forum.
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