Changed to canvas, wondering about this error, maybe the exam takes too long to load?

[Ben Brawn]

Hi Christian and others,

My institution swapped from blackboard to canvas, so I am uploading practice exams to see if everything works. I am not using the numbas LTI so I am using scorm. 

With a nice small exam, if I open it, do some questions and then reopen it, it says

 "Paused

The Exam has been suspended. Press Resume to continue.

You will be able to resume this session the next time you start this activity."

However, one exam I made has lots of questions. I notice if you open this exam and then sometime later open it again I get

"Warning! You may have this course open in another window. Opening this course in multiple windows can cause you to lose your progress.Cancel/Continue Anyway"

If I continue I normally get 

"Numbas has failed

Sorry, Numbas has encountered an error which means it can't continue. Below is a description of the error.

TypeError: Cannot read properties of undefined (reading 'loading')

TypeError: Cannot read properties of undefined (reading 'loading')
at scorm.SCORMStorage.examSuspendData (https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:40153:17)
at scorm.SCORMStorage.setSuspendData (https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:40179:25)
at scorm.SCORMStorage.saveQuestion (https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:40641:14)
at Numbas.Question.updateScore (https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:38269:34)
at Numbas.Question.addPart (https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:37672:14)
at https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:37406:27
at https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:39777:38
at new Promise ()

at https://syd.scorm.canvaslms.com/courses/sconeID/scone_prod.sha256_2e57f693d3db131a8d5cfc6b6b8eed162493f4ef7e8e51bb295049d8fb65d627/0/scripts.js:39772:24"

Any idea if this is a canvas error, a numbas error or just my mistake for making a huge exam?

TIA