Blackboard course menu disappears

We have heard of sporadic cases of students and faculty who open a Blackboard course and do not see the menu on the left side of the course. This appears to be related to opening Blackboard in a browser that has been sized under 1000 pixels which includes using a browser on a cell phone.  Clearing the browser cache or using a different browser will cause the menu to reappear. Students should use the Blackboard app instead of a browser on a cell phone to open Blackboard.