Hi Björn,
No problem. I'm not implying that the Vagrant install solves the problem you're having, I was just suggesting it as part of a process of elimination, as you mentioned you were running Ubuntu in a VM environment anyway, and this might help track down the source of the problem -- whether it is environmental or code.
I'm running the authoring tool the server/manual installation way, and on multiple (Ubuntu) servers, and I have never seen the issue you've mentioned before. Here are my versions:
- Node.js v 4.2.2
- npm 3.3.12
- grunt-cli v0.1.13
- grunt v0.4.5
- adapt-cli v2.0.2
Regards,
Brian