Meeting creation: creation from template and duplication didn't work

[MSoeb]

Description: The duplication of a (archived) meeting and creation of a meeting from a template doesn't work, if the base meeting contains mediafiles.

Reproduction:
It is necessary to have an existing instance which was updated with OS 4.1.15. The instance needs existing meetings with mediafiles and templates with mediafiles. Try to duplicate (archived) meetings or create a new meeting from a template.

What should happen:
Duplication of (archived) meetings and creation of meetings from templates with mediafiles should be possible.

[MSoeb]

The issue was solved with #2633