Assignment attempts can be seen by clicking the chevron in the cell and clicking Attempts.
Instructor can view all the attempts by following the below mentioned steps:
NOTE: This information applies to the Original Course View only. For more information about grading in Original course view see: https://help.blackboard.com/Learn/Instructor/Original/Grade
Grades in Ultra course view have a different user interface. For information on how grades are managed in Ultra course view see: https://help.blackboard.com/Learn/Instructor/Ultra/Grade