chore(*): Fix issue with nav when moving between different row dimension siblings.

Author: MKirova

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

@@ -721,6 +721,17 @@ export class IgxForOfDirective<T> implements OnInit, OnChanges, DoCheck, OnDestr
         return scroll;
     }
 
+    
+    /**
+     * Returns the index of the element at the specified offset.
+     * ```typescript
+     * this.parentVirtDir.getIndexAtScroll(100);
+     * ```
+     */
+     public getIndexAtScroll(scrollOffset: number) {
+        return this.getIndexAt(scrollOffset, this.sizesCache);
+    }
+
     /**
      * @hidden
      * Function that recalculates and updates cache sizes.

projects/igniteui-angular/src/lib/grids/pivot-grid/pivot-grid-navigation.service.ts

@@ -45,6 +45,19 @@ export class IgxPivotGridNavigationService extends IgxGridNavigationService {
             if ((key.includes('down')) && this.activeNode.row < this.findLastDataRowIndex()) {
                 newActiveNode.row = ctrl ? this.findLastDataRowIndex() : this.activeNode.row + 1;
             }
+
+            if (key.includes('left') || key.includes('right')) {
+                const prevRIndex = this.activeNode.row;
+                const prevScrContainer = this.grid.verticalRowDimScrollContainers.toArray()[this.activeNode.column];
+                const src = prevScrContainer.getScrollForIndex(prevRIndex);
+                newActiveNode.row = this.activeNode.mchCache && this.activeNode.mchCache.level === newActiveNode.column ?
+                    this.activeNode.mchCache.visibleIndex :
+                    verticalContainer.getIndexAtScroll(src);
+                newActiveNode.mchCache = {
+                    visibleIndex: this.activeNode.row,
+                    level: this.activeNode.column
+                };
+            }
             this.setActiveNode(newActiveNode);
             verticalContainer.scrollTo(newActiveNode.row);
         } else {