This issue is now resolved
Today (20th April 2023), Blackboard reported an issue which may have prevented some students from receiving submission receipts for Blackboard assignments, or which may be causing a delay to them being received. The Digital Education Office is working with Blackboard to investigate this issue and ensure it is resolved.
Update: Between around 12.00 and 1.15 today, a global Domain Name Server issue affected the blackboard.com domain, meaning that some services that need to access this domain were unable to. These included accessing Turnitin and Qwickly Attendance through Blackboard, and there was also a delay in submission receipts arriving (due to domain checks in mail servers). This issue has now been resolved, and all services should be working normally.