App icon doesn't show in the portal

Openproject icon doesn’t show in the portal anymore

I have a similar problem: the administrative Icons (“management link”) is not visible in the portal even after login as administrator. If I edit the portal - the icons are getting visible, if I close the edit session the icons are gone. administrative icons are restricted to administrators.

When I restart the server - the portal works normal, after some time (days?) the admin icons are not visible after login as they should.