synchronization via dropbox

Hi, I cannot synchronize my data base with dropbox anymore.
I work with 3 macs.
2 macs synchronize without problems (database and inbox)
mac 3 synchronizes without problems the inbox, but not the database.
I emptied the dropbox-contents, but cannot transfer the database from mac 3 into dropbox. In the activity window it reads “9 von 10 objection erledigt” and then it is stuck.
What can I try next? reinstalling devonthink pro on mac 3?

Open a ticket with Support.