bug: v7 => v8 Ion-split-pane + another ion-menu doesn’t work anymore

Hi,

We currently use Ionic v7 on our app and wanted to upgrade to v8, but we are facing an issue with the ion-split-pane and ion-menu, it worked fine on v7 but doesn’t work anymore on v8.
Our app use a ion-split-pane to display the main navigation menu on the left and the page on the other part of the ion-split-pane. And we chose to open another menu on the right side inside the ion-split-pane to perform some actions as create a new order, but the ion-menu on the right doesn't work on v8 while it works on v7.

There is a stackblitz showing the issue: [https://stackblitz.com/edit/v8ffjzmi-gpzs8mwn](https://stackblitz.com/edit/v8ffjzmi-gpzs8mwn)
And this one working fine on Ionic v7: [https://stackblitz.com/edit/v8ffjzmi-pf287qeh](https://stackblitz.com/edit/v8ffjzmi-pf287qeh)

Start by running the v8 StackBlitz reproduction and compare it with the linked v7 reproduction, focusing on the ion-split-pane containing the main ion-menu and the second ion-menu. Trace the Ionic menu and split-pane entry points involved in opening the right-side menu; done means the right-side menu works in v8 as it does in v7 without breaking the main navigation menu.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.