Hi Gunilla,
I have had exactly the same problem - we upgraded from 1.9.x to 2.2.11. We use online text assignment as a learner diary. Learners had no problem seeing the tutor feedback prior to upgrading but after upgrading nothing was visible. I now appear to have fixed it. I just started playing around with different settings and changed the grade from 'No grade' to 100. Then, for each learner where I have given feedback I awarded 10%. Now everyone can see the feedback. I really don't understand why this should make such a difference but I am just so glad to get it working again.