I , an Instructor, assign CK12 adaptive practice through canvas and I am happy with it for the most part. (I would like to select multiple chapter sections at once, but that is by-the-by. )
I set up the assignment so that CK12 is opened in a new tab.
Some (~10/50) of my students encounter an error message when hitting the CK12 "Turn-in" button after they have finished the adaptive practice. "Grading not enabled" was part of the error message. the students are doing the work in the classroom on Chromebooks
As a work around to the problem, I have students close the CK12 tab, go back to the assignment in canvas, open the CK12 tab again and then hit the "Turn in" button. This works.
So it seems that the linkage between the two platforms becomes unstable. It is possible that it is a network issue but I'm wondering if any one else has encountered the problem and found a more tangible solution.
@Rich_Sweetman I've been running into this error message as of late too! The exact wording of the error message that we receive is:
Please check with your teacher to ensure that grading has been enabled for this assignment in your LMS
We do the same practice as well -- instructors will use the practices as assignments in Canvas, students open up the CK-12 LTI by launching it in a new tab, then attempt to turn it in but receive that error message. Some students, if they wait, can turn it in a few minutes later but I suspect the behavior you've seen is the root cause of it.
The CK-12 documentation that I've been able to find is lacking in terms of some of these problems but they have one for Google Classroom that recommends those same steps you had. I wonder if it would be better to have the LTI load in the same page as opposed to a new tab maybe?