errorcode 12029

I shared a sheet with several people, and gave them full access. One person has no problems at all, an other person's data are not retained (i.e. not saved), and a third keeps getting the abovementioned errorcode when trying to insert rows. What can be the cause of the errorcode, and why does the sheet behave so differently for different people from the same group, sharing the same authorisations?

Kind regards,
Anton Langeler
alangeler