Video not shown in Courseware block

[pettobia]

Version
3.17

Describe the bug
When adding an Opencast block in Courseware as a lecturer, the video is shown at first. After switching to a student account, it just shows an error message "Es ist ein Verbindungsfehler zum Opencast Server aufgetreten. Das ausgewählte Video kann zurzeit nicht angezeigt werden.". When I re-switch to the lecturer account, it doesn't show the video anymore, too.

To Reproduce
Steps to reproduce the behavior:

1. create Opencast block in courseware
2. switch user

Expected behavior

Screenshots

[dennis531]

It seems that the authentication call (/lti) to Opencast is missing and only exists in the videos table.