fix(igxGrid): Fix offset when using virtual scrollbar with ratio.

Author: MKirova

projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts

@@ -271,8 +271,11 @@ export class IgxForOfDirective<T, U extends T[] = T[]> extends IgxForOfToken<T,U
     protected _differ: IterableDiffer<T> | null = null;
     protected _trackByFn: TrackByFunction<T>;
     protected individualSizeCache: number[] = [];
+    /**
+     * @hidden
+     */
     /** Internal track for scroll top that is being virtualized */
-    protected _virtScrollPosition = 0;
+    public _virtScrollPosition = 0;
     /** If the next onScroll event is triggered due to internal setting of scrollTop */
     protected _bScrollInternal = false;
     // End properties related to virtual height handling

projects/igniteui-angular/src/lib/grids/grid-base.directive.ts

@@ -3718,7 +3718,7 @@ export abstract class IgxGridBaseDirective implements GridType,
 
     protected getMergeCellOffset(rowData) {
         const index = rowData.dataIndex;
-        let offset = this.verticalScrollContainer.scrollPosition - this.verticalScrollContainer.getScrollForIndex(index);
+        let offset = this.verticalScrollContainer._virtScrollPosition - this.verticalScrollContainer.getScrollForIndex(index);
         if (this.hasPinnedRecords && this.isRowPinningToTop) {
             offset -= this.pinnedRowHeight;
         }