Hi @Anastasiia_Oharova ,
Yes, this is because the measure “Original estimate” is linked to the assignee and issue dimension and won’t work together with the “Logged by” dimension as there could be several user logging hours on one issue.
If the user is not changing, then one of the solutions is using the assignee dimension in rows and creating custom measures to represent the hours he/she spent, see the report example here: Logged hours by user on assigned and unassigned issues - Issues - Jira Demo - eazyBI
But as you mentioned that the assignee is changing, then another way how to create the report would be to have the Issue dimension in Rows to represent the “Original estimate” (with a measure that uses the changing context, see a similar thread below). And then add “Logged by” user with measure “Hours spent”.
best,
Gerda // support@eazyBI.com