When I click on Collaborate in my Blackboard course, it hangs or freezes and I can't see the sessions to choose from
This is related to Chrome blocking 3rd Party Cookies.
You will see in the browser address bar a small symbol with a red cross, click on this and then select MANAGE:
Next, ensure the setting "Block third-party cookies" is switched OFF:
Reload the page and you should now see any collaborate rooms set up with the Blackboard Course.
Staff - please contact LTD Support if you have any queries.