https://stackblitz.com/edit/angular-5elhtu?file=src%2Fapp%2Fapp.component.ts

When a detail row is used, the moment you expand one row and scroll, it automatically loads the last items from the dataset.

Ex expand row 1 - start scrolling, and it suddenly loads 5xx th row+;

When grouping is also enabled - expanding the detail row under one group, expands it under all groups.

The stackbliz is from the kendo demo page for virtualscroll (with the added detail row).