A brief bit of recent history: with the introduction of DTTG3 a number of users noticed that a small number of files were being damaged in the sense that they continued to exist but had no content. They were 0 kb in size, and became dubbed “ghost files”. The reasons for the damage are - to my knowledge - still under investigation, but are assumed to be due to a bug in a long past version of DTTG2 which propagated via the sync store. One of the mitigations implemented by DEVONtech was to include a mechanism in both DT and DTTG which stops sync when empty files are present; this way, propagation of the defect could be stopped. Whilst some file formats are assumed to be acceptable even when they are 0-size, others trigger the safety mechanism.
Sync errors are logged; depending on your configuration, the log window will open automatically when an entry is written. In addition, the warning triangle symbol at the top right of your DT3 window will “light up”. In DTTG the cloud symbol will be superimposed with a small triangle.
If this safety mechanism is causing trouble for you, you could set up a smart rule which deletes any 0-size files prior to sync:
Do be clear on the ramifications of this, though; a script which lists those documents and asks for permission to delete them (instead of the delete action in the smart rule) might well be a better choice. Also be clear that groups etc. are all 0-size; the rule must include the “kind is any document” provisor.
@cgrunenberg might this safety mechanism be something which could be turned off via a hidden preference? It might well not be desirable for every user to delete all their empty files to be able to sync.