Case stakeholders' permissions are not propagated to stages

See the attached case model and to reproduce the issue follow the steps below:

1) Case was started with user Ali.
2) Task1 was started and completed with user robin (mapped to* role patient*).
3) Task2 was attempted to be triggered with user ali - this didn't work and failed with "user ali doesn't have permission to access case XY"
4) Task2 was triggered with user robin - this worked OK.
5) Task2 was started and completed with user ALI - this worked.
6) CaseFile was attempted to be updated with user ALi - this fail with the same permission issue, and it works with user Robin.
7) Expected behavior is that user Ali - as a case owner - will have permissions to manipulate the case throughout its lifetime