Description

When modifying items that use MVC presentation components in the Page Editor, some placeholders may not be editable, even though the corresponding placeholder settings are configured to allow editing.
This happens when the corresponding placeholder key contains uppercase characters, for example "MainContent".

Solution 1

Use lowercase placeholder keys.

Solution 2

Apply the Sitecore patch as follows:

1. Copy the attached Sitecore.Support.424797.dll file to the \bin folder.
2. Copy the attached Sitecore.Support.424797.config file to the \App_Config\Include folder.