Update 5/24/19: Fixed! We still recommend using Group Tag instead of Order ID moving forward but for now Order ID has been added back in the backend.
We recently made a change in how you can import Windows Autopilot devices from a .csv file. In the 1905 service update to Intune, the option for Order ID was changed to Group Tag instead. As a result, Order ID tag does not get set when importing devices through AutoPilot using a .csv and is not populated for imported devices. There are, however, no errors notifications shown in the console.
We are working on fixing this in the service and will also shortly be adding this to the What's New page. Until then, as a workaround, if you are importing devices using OrderID, you can change the column in the .csv file used for importing from “OrderID” to “Group Tag”.