We are currently running into the issue that the spent time report from a parent task does not work properly when confronted with sub tasks from different projects.

So we are running a structure similar to this:

• Projects ** P1_Particular customer project
• Global helpdesk

Hence, the ticket hierarchy would look like this:

• @#1@: Parent task => Global helpdesk
• @#2@: Development task => subtask of @#1@, located in project P1

On the parent task's detail page @#1@, all time entries tracked against any of the sub tasks are calculated correctly (including those sub tasks from other projects).
However, when clicking on the calculated time, the spent time report shows up, including spent time entries for the current project only and hence displaying incorrect values (mostly zero).

A temporary workaround for us is to visit the spent time report not directly from the project but from the global perspective which shows correct values.

So to conclude:

• This URL here does not work: https://redmine_base_domain/projects/helpdesk/time_entries?issue_id=%7E1
• This URL here shows correct values (mind that it does not contain the project reference): https://redmine_base_domain/time_entries?issue_id=%7E1

Given the fact that the calculation on the parent task's detail page works correctly, I would consider this a bug.

Currently running Redmine v3.4.5. In case you need more information to reproduce this behaviour, I will be glad to support.