One issue I am encountering is that the scroll-bar appears when the expansion panel is collapsed, but not when it's expanded. Here are the references: Collapsed Expanded
<mat-expansion-panel class="panel">
<mat-expansion-panel-header>
<mat-panel-title>HH:MM:SS</mat-panel-title>
<mat-panel-description>Foo</mat-panel-description>
</mat-expansion-panel-header>
</mat-expansion-panel>
.panel {
max-height: 1500px;
width: 1000px;
overflow: auto;
}
When the expansion panel is expanded, the scroll-bar behaves as expected.