We are finding that for random courses, the Review Panel on the left when grading an assignment is not showing up. Also the three buttons on the bottom right are missing: Collapse Review Panel, Restore Default Layout and Collapse Grade Panel.
It is happening in random courses after the upgrade. Using Version 3.5.1.
We're experiencing the exact same problem. If I find a resolution I shall let you know!
There is a new option in the Assignment setup page called 'Annotate PDF' which explicitly needs to be ticked to show the learner work and the review panel options.
Curiously, after upgrade, some of our assignments have this ticked and some don't. Not sure of the reason why, but at least know how to resolve it.
Sarah, we are experiencing the same issue in our upgraded 3.5.1 system, and your fix seems to work for us, also.
Thanks for sharing!