When you get the following error: "The string for textgroup blocks is not allowed for translation because of its text format" it's because you have to enable translation for your text formats (text formats are the options you see below the body area while creating or editing a node, such as: Full HTML or Filtered HTML). Some text formats are disabled by default so to enable them follow these steps:
- Make sure you are logged in and go to 'Configuration'.
- Scroll down and go to 'Multilingual settings' below the 'Regional and language' header.
- Now click on the 'Strings' tab in the right upper corner.
- Below 'Translatable text formats' you can now enable or disable
- Problem solved!
They tried to hide it, but we found it!