There is a known problem for anyone with a Mac who has upgraded to Safari version 11.1.
Students attempting to upload an assignment may have a missing upload button or, more likely, will get an error message: Failed to submit Assignment. Please try again. When trying again, the student gets the same message.
Students can try the upload in another browser on their Mac, but that also seems to be a problem. The Safari upgrade seems to corrupt the upload process entirely for the student on that unit.
One work-around is to do the upload on a PC.
Faculty: If the PC upload is not a viable option for the student, faculty are encouraged to determine what options may be possible within the scope of the course.
Students: Contact your instructor directly for instructions on what to do next. Do not wait for an assignment to be due, if possible.
The original Blackboard notice can be found on the Blackboard knowledge-base site.
A fix is planned for an upcoming Blackboard update, but there currently (April 2018) is no estimated date on when that may be installed.
If faculty need assistance with this issue, contact Harold Strassner or Judie Littlejohn for assistance. Email can be sent to firstname.lastname@example.org and the folk there will route your request to Harold or Judie.