A student in one of our courses has received the error 'Grader limit has been reached. No further feedback required' on at least two occassions while using the student annotation tool to submit their work. The student is able to submit their work after exiting and reloading the page and restarting the work using student annotation, however in doing so they lose their previous work. 

I have tried using student view and attempted to use the annotation tool to see if the page would max out at a certain amount of characters, but I was unable to replicate the error.

I have been unable to find reference to a similar error message in the guides or question forum - any help would be appreciated.