Edit Page disabled in Page Layout

"Edit Page" option in my page layout is no more enabled / available.
After further examination, it has been found that the edit page option has been made unavailable due to the fact that there are no SharePoint controls in the display mode.

In my case, I am loading an iFrame in the display mode of the page which loads an aspx page.

I fixed this issue by adding a SharePoint control and by marking it as hidden.

Code:

<div style="display:none;">
  <SharePointWebControls:FieldValue runat="server" id="TitleFieldValue" FieldName="Title"/>
</div>
<PublishingWebControls:EditModePanel runat="server" PageDisplayMode="Display" SuppressTag="true">
  <!-- Code here -->
</PublishingWebControls:EditModePanel>
<PublishingWebControls:EditModePanel runat="server" PageDisplayMode="Edit" SuppressTag="true">
  <!-- Code here -->
</PublishingWebControls:EditModePanel>