I feel you are waiting here for something, Kasia.
I was too, because I forgot about this requirement I heard people talking about some days ago, but it came back to me right now.
quizaccess_onesession lets restrict one quiz attempt to being able to be done only from one browser session. That hinders you to start a quiz, then having your expert continuing it from another device.
It turns out that disabling this in the case of need (whoever wants to emphasize the use case better than me please do comment!) is quite cumbersome. Therefore quizaccess_onesession cannot really be recommended to everyday (non expert) lecturers. One such event happening could be: a net outage happens, then the net returns. Then everyone wants to continue their attempts. But due to the fact, maybe, that they had to log in again, the sessions have changed. Now everyone is blocked. Another use case: a client crashes, no restart possible and even if possible it would be another browser session.
Target:
Overhaul that quiz access rule. User friendliness ("Select all" is maybe missing? Sorry for my ignorance, I'm not a power user.). "Quick solution" in case need be.
It might be useful to contact the maintainer beforehand and offering help/ask of his consent.
Best,
Luca