Currently, Paper Trading does not support placing orders on delayed data feed. In case the letter “D” is displayed next to the symbol title, the updates are not in real-time.
To learn more about the period of delay and required real-time data package, please click on this icon:
Kindly note, our paid plans don’t give you access to official real-time data from the exchanges unless this data is free by default (e.g. FX or Cryptocurrencies). Most of the stock exchanges that we support charge fees for real-time data, and we are unable to cover those costs even if you have a paid plan.
The available markets and prices are displayed on this page.
2. Also, a non-tradable symbol notification appears on indices, as these symbols are not supported for trading in general, for example NASDAQ:NDX.
However, it is possible to select CFD on index and place orders there. CFDs are updated in real-time and free by default.  The symbol type can be checked in the symbol search, next to the data feed name.