I have not received a solution from Canvas support or community; however, I did get some feedback from SchoolNet via DPI (I haven't been able to determine whether the workaround is successful at this point as I have not had any teachers try it yet)...
Pearson continues to investigate the error message to determine a root cause. Thank you to everyone for supplying login credentials, Schoolnet Test ID numbers, Canvas URL links to assessments, ETC. We know this is a tremendous ask and truly appreciate everyone's assistance with gathering the details.
We were able to reproduce the issue via the following click path:
Student authentication through IAM/NCEDCloud > click Canvas > select course > select assessment from To Do list > error appears
WORKAROUND:
If the error occurs for your students, please have the student(s):
1. Exit/log out of Canvas.
2. Next, from the NCEDCloud launch page click Schoolnet App.
3. Navigate back to NCEDCloud launch page and click Canvas to access the assessment.
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