The problem occurs both in our production environment

Environment:
  Redmine version                4.2.3.stable.21378
  Ruby version                   2.5.5-p157 (2019-03-15) [x86_64-linux-gnu]
  Rails version                  5.2.6
  Environment                    production
  Database adapter               Mysql2
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                sendmail
SCM:
  Subversion                     1.10.4
  Git                            2.33.1
  Filesystem
Redmine plugins:
  redmine_agile                  1.6.2
  redmine_checklists             3.1.20
  redmine_theme_changer          0.4.0

and our test environment for the update to Redmine 5.0.0

Environment:
  Redmine version                5.0.0.stable.21535
  Ruby version                   2.5.5-p157 (2019-03-15) [x86_64-linux-gnu]
  Rails version                  6.1.5
  Environment                    production
  Database adapter               Mysql2
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                sendmail
Redmine settings:
  Redmine theme                  Default
SCM:
  Subversion                     1.10.4
  Mercurial                      4.8.2
  Git                            2.33.1
  Filesystem
Redmine plugins:
  redmine_agile                  1.6.4
  redmine_checklists             3.1.21
  redmine_theme_changer          0.5.0

Both are using MariaDB 10.6.

We have our permissions set up so new tickets by the affected role ("Manager Extern") can only be created in the tracker Inbox and the user can not select an assignee.

!selection_20220422_132320.png!

!selection_20220422_132332.png!

!selection_20220422_132428.png!

We have three projects, two of them child-projects of the third but without inherit members. A user is a member with the affected role in both of them (but not the third). The Project field that makes this issue possible does not appear in unrelated projects it seems. In my minimal tests I did not enable the Agile plugin modules in the test projects.

The Inbox Tracker setup works when creating an issue the normal way (without changing the Project field) but when using the "New Issue" button while in Project A and then changing the Project field to Project B (even though the user has the same role in both) the assignee field becomes visible in the create issue form, custom fields of the project are not displayed correctly and - even though the tracker field does not become visible - the issue is created in the global default tracker (Fehler) instead of the Inbox tracker.

I would expect the permissions for visible fields and tracker restrictions on newly created issues to be honoured even when tickets are created via this route and of course the displayed form fields to reflect that.

Forms before and after changing the project field (keep in mind both projects are configured exactly identically):

!selection_20220422_135532.png!

!selection_20220422_135547.png!