I had also same issue, i resolved this issue by increasing the Number of Calls per Request in 'Apache Sling Main Servlet'.Knowledge Transfer: Not able to edit components in Touch UI in AEM 

Below is datasource.jsp for adding dynamic dropdown into my customComponent dialog, I'm using this datasource in my customComponent as below mentioned <dataSourceTest> field.Here my requirement is need to get url values to dropdown when my customComponent used in any page(this page having urls). So ...

Below is datasource.jsp for adding dynamic dropdown into my customComponent dialog, I'm using this datasource in my customComponent as below mentioned <dataSourceTest> field.Here my requirement is need to get url values to dropdown when my customComponent used in any page(this page having urls). So ...