Steps to Reproduce:
1. Start a Liferay DXP
2. Create a custom theme for 7.2
3. Create a new site and add at least one public page.
4. Apply the custom theme to the site's public pages.
5. Open Internet Explorer 11 and sign in.
6. Navigate to the site.
7. Attempt to toggle the control panel.
Control panel can be toggled.
Control panel cannot be toggled. This may take several tries to reproduce. Refresh the page and try toggling.