power query custom data type

Hey Dicken,

Your M code is perfect Table.CombineColumnsToRecord with TypeName="Excel.DataType" is exactly what the UI generates. The issue is almost certainly your subscription SKU.

Your build (2603, 19822.20086) is Current Channel Preview from 18 March 2026. You are ahead of most users, not behind, so it is not a version problem.

The catch is creating a custom Power Query data type as a rich linked data type in the worksheet (card icon, Insert Data button, dot-notation) has historically been gated to Microsoft 365 Apps for Business / Enterprise. On M365 Family / Personal, the M code runs and the record column loads, but you do not get the card experience from the BCTI video. Microsoft's docs are vague ("supported in Microsoft 365"), but Mynda Treacy confirmed the same symptom on her MOTH article. Business sub required, consumer Home would not do it.

Two quick checks before you conclude:

1. File → Account confirm it says Microsoft 365 Family/Personal. If any second (work/school) account is signed in anywhere in Office, log it fully out a non-qualifying account in the session can suppress linked data types even for the qualifying one.
2. Try the same workbook in Excel for the web. The web app is more permissive than consumer desktop. If the card appears there but not on desktop, definitely it is the desktop's SKU gate.

On the date quirk: that's the Lotus 1-2-3 leap-year bug Excel has carried since 1987. Excel's serial calendar pretends 29 Feb 1900 exists which was not a leap year. Power Query uses a correct calendar, so any date on or before 28 Feb 1900 is off by one between the two. 1 March 1900 onward lines up perfectly.

For Detailed Information:

• Create a data type (Power Query)
• Linked data types FAQ and tips
• Power Query Custom Data Types - My Online Training Hub
• The M Behind The New Power Query Data Types In Excel
• Excel incorrectly assumes that the year 1900 is a leap year

Best Regards,
Nasif Azam