Long ago, I purchased the RotR bundle, then stopped playing before all of its content was released. I recently returned to PACG but the purchased content is no where to be found (but I am given plenty of options to purchase again). Is there a straightforward method for resolving this issue?

Check out that your game Center or google play account is the same that you used in buying the content. If it is and you still most some content, contact the support@obsidian.net