So I'm really curious, where do you think it's documented that date functions don't work in date validations? Change the extended date to normal and it works fine. As shown in another post above, Microsoft doesn't imply in any way, that I can see, that there should be a problem with their own example with extended dates.
here for one...
https://support.microsoft.com/en-us/...0-9851042e0024
Warning When you create expressions and use date/time functions based on the Date/Time Extended data type in Access, you may lose precision in calculations or encounter other problems with the results. We are aware of this issue and plan to better support expressions and functions in an upcoming release. As a workaround, you can Create a pass-through query to use the equivalent SQL Server expression and date/time functions. For more information, see Comparing Access SQL with SQL Server TSQL.
As far as I can see the only current use for Date/Time Extended is for compatibility with sql server date/Time2 datatype.
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