There is an issue with the forums breadcrumbs.
Create two separate forums each with topics
Click the Lessons tool
Choose add forum topic.
Link to a topic in your first forum and save
Choose add forum topic again
Link to a topic in your second forum and save
Now click the link to the first forum topic. The breadcrumb trail is correct.
Go back to Lessons
Click the link to the 2nd forum topic. The topic is correct, but the breadcrumb will show you are still in the first forum.