Yes blackboard is absolutely horrible. One of (many) experiences I had, was a course coordinator for a project course where students submitted a research report at the end. We needed to get the reports uploaded to turnitin through the platform, the interface for doing this was horrible enough, you essentially needed to check the reports in a big table and press upload selected to turnitin. The thing would just randomly fail and no reports would be generated. After much fiddling I found that the process failed likely (I don't quite remember how I found this) because in the background blackboard would generate a zip or tarfile and then upload that to turnitin. The thing was the VMs they seemed used were horribly under provisioned, so the zip or tar process would run out of memory and be killed. The thing was, there was no easy way of knowing how many reports reliably worked, so the solution (proposed by blackboard support) was I should just go to every report individually and upload. A process that took about 3 h because the interface was so horribly slow. Considering that I was already completely overworked (80h weeks) not a suitable solution.

Fortunately, many universities are moving to other platforms. Where I am now we use canvas, which is open source and really like night and day compared to blackboard. I also heard good things about moodle (another OSS solution).