@stj1120
Some of the Alteryx inbuilt functions are really powerful, like the DateTimeParse function, especially if your date are coming in forms of complex strings.
In your case you can use a formula tool with the below expression -
DateTimeParse([APPT_END_DT],"%y-%m-%d")
Hopefully, this resolves your issue. Let me know if this isn't what you were looking for.
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Best,
Raghav
"Keep Alter-ing Lives"