I add and update some issues through REST API. Everything works fine, I can see the changes when I view the issues directly. Also the journal of the issue shows the changes.
But on the Activities page there is no sign of these changes.
My Redmine version is 3.4.2
Is this a bug, or have I misconfigured something?
A few suggestions:
You could try, in a Rails console:
Redmine::Activity.providers #(you should have "Journal" is there)
Check the date of the last Journal:
On your "Activity" screen, make sure "Issues" is not unchecked in the right pane.
Make sure the user has appropriate permissions on the relevant projet(s).