Unable to create transformation in Data Table

[Porter76]

I am trying to create a transformation in one of our data tables. I want to add a column called "Destination" or change the name of a field that is under a pre existing column with a dropdown.

When I go to the LA workspace and try to create a transformation, I don't have the option for some reason.

[#2]

Custom Table (classic) doesnt support Transformation, see here to convert them: https://learn.microsoft.com/en-gb/azure/azure-monitor/logs/custom-logs-migrate