When adding apps on SharePoint 2013, we can add apps from our organization app catalog or the built-in apps like Tasks and Customs Lists. This works well when using the default master page. The app selection view looks as shown below:
When applying a custom master page, we usually tend to remove some of the content containers (ContentPlaceHolder) that we may not need. This can cause some side effects on some of the SharePoint components that may depend on those containers. In our case, we had removed one of the following items:
Server Side Markup
<asp:ContentPlaceHolder id="PlaceHolderPageTitleInTitleArea" runat="server" />
<asp:ContentPlaceHolder ID="PlaceHolderLeftNavBar" runat="server">
As shown above, the Apps you can add section is no longer visible. In some cases, the container declaration may exist, but it is set to Visible="False". This can also cause the rendering problem.
To address this problem, we can add the tags on the master page and test the rendering of the view. The next step is to address the layout issues that this can cause on our custom master page. For that, we need to use some CSS magic to remove any of the content that we do not want displayed on our views. An approach is to override some of the classes that are found on the inner child elements as that should not affect how the add an app section is rendered.
Hope this helps.