Dropbox IO does not sync

Hi All,

I was running OpenHAB on a Mac before and then decided to switch to a Ubuntu server.
Everything seems to work fine except the Dropbox IO.

There is not any single message in the log but the behavior is really strange.
It looks like the download (from dropbox to my openhab) does not work at all in all directories.
But the upload works (from openhab to Dropbox) only if I modify a file within /usr/share/openhab/configurations (/etc/open/configurations). If I modify a file within a subfolder it does not work.

All folder in openhab have owner openhab/openhab.
Dropbox is installed and correctly sync file locally on my unbuntu.

So for me it looks like teh binding only check changes of local file in one folder.

Is there anyone who have an idea of what I could do?

I am using openhab 1.8.3 freshly installed on ubuntu 16 server with java 8.
As the upload works for one directory I assume the service is running.