Hello. 

Thank you for the shared details related to the Native Grid's behavior when there are no columns defined for the component. This issue is a known one and its public thread can be checked on this link to our public repository. As the Grid requires either columns definition or data before its initialization, we don't thread the discussed behavior as a bug but as a feature enhancement. 

As the scenario is not listed in the Feedback portal of Kendo UI for Vue internally related your report with the feature enhancement in our public repository. I also raised the priority of the enhancement. 

The solution you can use to load the data that is fetched in the mounted hook of a Vue component, we can use the approach demonstrated in this StackBlitz example. In this example, we use a dummy object to define the variable passed to the columns property of the Grid. 

columns: [{ field: "ProductID" }],

Once the mounted function is triggered, we reset the columns prop value and after that assign the Grid's data.

mounted: function () {
  this.columns = [];
  this.gridData = this.getData(this.employees);
}

Please check the above example and try the suggested approach in your application. If you have any questions related to the provided solution or need furhter assistance with the current ticket, we will be happy to help you.

Looking forward to your reply.

Regards,
Petar
Progress Telerik