projects/igniteui-angular/src/lib/core/styles/components/grid-toolbar/_grid-toolbar-theme.scss

@@ -92,6 +92,17 @@
     ));
 }
 
+@mixin _offset-sibling-elements($offset) {
+    + igx-grid-header-row,
+    + igx-grid-group-by-area {
+        margin-top: $offset;
+    }
+
+    + igx-grid-group-by-area {
+        height: auto;
+    }
+}
+
 /// @param {Map} $theme - The theme used to style the component.
 @mixin grid-toolbar($theme) {
     @include css-vars($theme);
@@ -121,6 +132,9 @@
     );
 
     %igx-grid-toolbar {
+        $height: map.get($grid-toolbar-height, 'comfortable');
+        @include _offset-sibling-elements($height);
+
         position: absolute;
         width: 100%;
         display: flex;
@@ -137,7 +151,7 @@
 
         background: var-get($theme, 'background-color');
         height: auto;
-        min-height: map.get($grid-toolbar-height, 'comfortable');
+        min-height: $height;
         padding-block: 0;
         padding-inline: map.get($grid-toolbar-padding, 'comfortable');
 
@@ -165,37 +179,30 @@
                 }
             }
         }
-
-        + igx-grid-header-row {
-            margin-top: map.get($grid-toolbar-height, 'comfortable');
-        }
     }
 
-
     %igx-grid-toolbar--cosy {
-        min-height: map.get($grid-toolbar-height, 'cosy');
+        $height: map.get($grid-toolbar-height, 'cosy');
+        @include _offset-sibling-elements($height);
+
+        min-height: $height;
         padding-inline: map.get($grid-toolbar-padding, 'cosy');
 
         [igxButton] {
             margin-inline-start: map.get($grid-toolbar-spacer, 'cosy');
         }
-
-        + igx-grid-header-row {
-            margin-top: map.get($grid-toolbar-height, 'cosy');
-        }
     }
 
     %igx-grid-toolbar--compact {
-        min-height: map.get($grid-toolbar-height, 'compact');
+        $height: map.get($grid-toolbar-height, 'compact');
+        @include _offset-sibling-elements($height);
+
+        min-height: $height;
         padding-inline: map.get($grid-toolbar-padding, 'compact');
 
         [igxButton] {
             margin-inline-start: map.get($grid-toolbar-spacer, 'compact');
         }
-
-        + igx-grid-header-row {
-            margin-top: map.get($grid-toolbar-height, 'compact');
-        }
     }
 
     %igx-grid-toolbar__title {

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

@@ -7235,35 +7235,32 @@ export abstract class IgxGridBaseDirective extends DisplayDensityBase implements
             const expansionRowIndexes = [];
             for (const [key, value] of this.expansionStates.entries()) {
                 if (value) {
-                    expansionRowIndexes.push(key);
+                    const rowIndex = this.gridAPI.get_rec_index_by_id(key, this.dataView);
+                    expansionRowIndexes.push(rowIndex);
                 }
             }
             if (this.selectionService.selection.size > 0) {
                 if (expansionRowIndexes.length > 0) {
                     for (const [key, value] of this.selectionService.selection.entries()) {
                         let updatedKey = key;
-                        expansionRowIndexes.forEach(row => {
-                            let rowIndex;
-                            if (!isNaN(row.ID)) {
-                                rowIndex = Number(row.ID);
-                            } else {
-                                rowIndex = Number(row);
-                            }
-
-                            if (updatedKey > Number(rowIndex)) {
-                                updatedKey--;
+                        let subtract = 0;
+                        expansionRowIndexes.forEach((row) => {
+                            if (updatedKey > Number(row)) {
+                                subtract++;
                             }
                         });
-                        selectionCollection.set(updatedKey, value);
+                        selectionCollection.set(updatedKey - subtract, value);
                     }
                 }
             } else if (activeEl) {
+                let subtract = 0;
                 if (expansionRowIndexes.length > 0) {
                     expansionRowIndexes.forEach(row => {
                         if (activeEl.row > Number(row)) {
-                            activeEl.row--;
+                            subtract++;
                         }
                     });
+                    activeEl.row -= subtract;
                 }
             }
         }
@@ -7614,8 +7611,9 @@ export abstract class IgxGridBaseDirective extends DisplayDensityBase implements
                 });
             });
         });
-
-        this.hideOverlays();
+        if(!this.navigation.isColumnFullyVisible(this.navigation.lastColumnIndex)) {
+            this.hideOverlays();
+        }
         const args: IGridScrollEventArgs = { direction: 'horizontal', event, scrollPosition: this.headerContainer.scrollPosition };
         this.gridScroll.emit(args);
     }